The Grey Blog

Adobe Photoshop Lightroom: How I Share Catalogs Across Different Devices In a Networked Environment

2012-01-27T20:58:00.001+01:00

During my workflow as an amateur photographer I'm using Adobe Lightroom and Photoshop on Mac OS X. As many of you already know, Lightroom does not allow you to use a catalog on a network share. That doesn't mean, however, that all your hopes of easily replicating it across different devices are lost. This is what I'm doing and to replicate it you will need:

An NFS server: there are many operating systems that can easily be configured as NFS servers. The quickest way to go it's probably GNU/Linux. Personally, I opt for Solaris and I'll tell you why in a few minutes.
The ability to mount NFS file system from your client devices: this is easily accomplished in every operating system supported by Lightroom.
A way to easily synchronize your catalog across the different client devices you will use. I use rsync.

NFS Server

My photos are stored on remote storage, published using the NFS protocol, and accessible from any client I need to work from. The NFS server in my home setup is not only the place that publishes my data: it's also the place that stores it. Personal data is valuable. That's why I'm replicating it in a configuration of hard disk drives with a high level of redundancy. Even so, really important things are backed up regularly. Do not use non-redundant storage for long term storage of your data. Stay away from those cheap "storage servers" built into a single disk drive. No matter how good the brand or how much it costed, any drive will fail: you just ignore when it's going to happen.

The first difficulty to overcome when dealing with personal storage is: easy of use. I bet many of us would not adopt a solution, no matter how good, that badly impairs our user experience. Fortunately, though, it's very easy to build a relatively cheap home storage solution that fulfills all our needs. However, I'm not going to explain you how: just search the Internet and you'll discover plenty of different options that are available to you.

My home storage solution is built upon Solaris. Explaining why and all the benefits I enjoy would be too extensive: I'll just say I love the ZFS file system. ZFS and Solaris are the stone that killed so many birds that I don't imagine living without it.

First of all, it's ridiculously simple to export a ZFS file system using the NFS protocol. In some cases I export other kinds of target, such as iSCSI, which I need to have Time Machine working onto remote storage. If you're interested, you can check an old post about it.

NFS Client

Once you've installed your favorite NFS server of choice, it's time to use it. Windows ships with good and native NFS support at least since Vista and if you're using ZFS you will also be able to access ZFS snapshots from the Windows UI. UNIX and UNIX-like operating systems, such as Mac OS X and GNU/Linux, usually have good NFS support as well.

If you're using Mac OS X, mounting an NFS file system is a no brainer. Just open the Finder, select Go/Connect to Server… and just write the address of your NFS server.

Finder - Connect to Server...

OS X will mount the NFS share and it will appear as a new network drive:

Finder - Mounted NFS Share Mounted Displayed as a Network Drive

When organizing photos in Lightroom, just store them into this drive. As far as it concerns Lightroom, there's absolutely no difference when working on photos on your local hard disk or with photos on a network share such as this. In the next picture you can see the Folders panel in Lightroom Library module showing how I'm storing my photos on that NFS share.

Lightroom - Folders Panel

Synchronizing the Catalogs

Now everything but one thing, the catalog itself, is stored on the network in a location accessible from all your clients. The last problem is synchronizing the catalog across devices.

Of course, I'm using an NFS file system to store a copy of the catalogs too. The only thing we need to do is:

Synchronize it on the NFS share when leaving a device.
Synchronize it back from the NFS share when using another device.

This sounds difficult but it absolutely is not. Moreover, always performing a synchronization of your catalog is a good practice that will protect you from losing it because of missing or improper backup policies.

You might be wondering that the synchronization of a big catalog could take a lot of time. Well, it certainly could, if done naïvely with the inappropriate tools. A tool such rsync, for example, will help keeping synchronization times to a minimum taking care of just synchronizing the differences between the two catalog copies.

Another good news for Mac OS X user is the following: Mac OS X ships with rsync, you won't need to install anything on your Mac OS X devices.

Synchronizing an entire directory tree with rsync is "trivial", but it requires some command line proficiency:

$ rsync -az --inplace --delete [local-catalog] [remote-catalog-parent]

rsync has got plenty of options: the previous command is a good starting point to begin synchronizing your catalogs while you learn using rsync.

To synchronize the catalog back to another device, just change the source with the target:

$ rsync -az --inplace --delete [remote-catalog] [local-catalog-parent]

In my case, for example, I'd run the following line when synchronizing a catalog to the NFS server:

$ rsync -az --inplace --delete /Users/enricomariacrisostomo/Pictures/Lightroom /Volumes/enrico/lightroom-backup

On the other hand, when I need to synchronize a local device against the remote catalog, I just run the following:

$ rsync -az --inplace --delete /Volumes/enrico/lightroom-backup/Lightroom /Users/enricomariacrisostomo/Pictures

A Word of Warning: do not use trailing slashes in the previous commands unless you know what you're doing. If both source and target are directories, and you're not using trailing slashes, rsync will synchronize the source directory into a subdirectory of the target directory. In the previous example, rsync is creating a Lightroom directory inside lightroom-backup.

To speed things up, just create shell scripts with your synchronization commands and run them when you need them.

These commands may sound scary if you're not accustomed to using the terminal. However, I think the benefit is worth the trouble. If you don't want to fiddle with the terminal, ask a friend of yours to write the scripts for you. Also, you may find decent rsync GUIs out there, should you prefer using one.

Just to give you an idea of how efficient rsync is, here's an example: I just imported 20 RAW files into a catalog of mine and worked on them. This catalog is managing more than 10.000 images and is made up of more than 45.000 files. Here's the tail of the rsync output log of the last synchronization:

sent 34421438 bytes received 231055 bytes 2772199.44 bytes/sec
total size is 16648567921 speedup is 480.44

Pretty fast, isn't it? When you get used to it, you can't live without it.

Further Steps

Depending on how your catalog is configured, you may want to synchronize your Lightroom presets as well. Please check this post for further information. The technique to synchronize them will be exactly the same technique we used for catalogs.

Misty Sunset on a Mancha Plain

2012-01-26T11:18:00.003+01:00

A couple of weeks ago I was on a AVE (a Spanish high-speed train) coming back home from Málaga. The trip lasts two hours and a half and I was pretty tired and half asleep when the sunset caught my attention. The train had just passed Ciudad Real, a city in Castilla-La Mancha, and found itself in the middle of a plain. A few kilometers away, just in front of some small hills, there was some mist that could be easily confused with a cloud. The atmosphere was incredibly clean and since the sun had just set behind the hills there was a nice luminance gradient in the sky: from a deep blue (not really caught in the shot because it's landscape oriented) to a very bright yellow and orange shades. That was really worth a shot.

The train was moving at almost 300 km/h (186 mph) and the lighting in it was pretty strong. However, I came out with a decent shot I'm sharing with you. When I took it I had a black and white picture in mind. However, the colors were beautiful and I'm going to share both versions with you.

Misty Sunset on a Mancha Plain - Color

Misty Sunset on a Mancha Plain - Duotone Sepia

If you want to see them bigger, the images in this blog are linked with the original pictures in Flickr.

Adobe Photoshop Lightroom 4 Beta 1: The New Development Process

2012-01-19T11:51:00.001+01:00

A few days ago Adobe released the first beta preview of the upcoming release of Adobe Photoshop Lightroom 4. This Beta release introduces many new features and a new development process (2012).

The new development process is at least as intuitive as its predecessor, although it's been fundamentally redesigned. At first, it may seem pretty different, especially when you compare the result you obtain applying the "same" adjustment in the previous process (2010) and in the new one.

In fact, despite the need of getting used to the new tool, I believe that the new process is both more intuitive and more powerful.

Neutral Defaults

The first thing you'll notice when importing a photo into Lightroom 4 is that default settings are more neutral. Lightroom 3 defaults introduce a bit of contrast in two places:

The Blacks slider is set to 5, shifting down the black point a bit.
The tone curve is set to Medium Contrast.

While it's true that we're very often pushing the contrast a bit, I don't like Lightroom doing it for me during the import phase. In fact, I usually reset those settings either manually or with a preset just while importing. Lightroom 4, on the other hand, just lets your image untouched: the only setting that's still applied is the Adobe Standard profile in the Camera Calibration panel.

Although it may seem a minor problem, it also has a serious impact on the effect of other controls, such as the Exposure control, on Lightroom 3. This problem is not only evident on low key images, or images with dark shadows, but also on images whose exposure you need to increase more than a bit. Why? Because Blacks is used to set the black clipping point. When it's set, Lightroom will try to preserve it: if you shift rights or expand the histogram more than a bit, results may start to look unnatural.

Look at this image:

Underexposed Image

When I shot it, I voluntarily underexposed it: I had no tripod, the camera ISO was already set to maximum, but the shutter speed was too slow. After import Lightroom defaults were applied. Let's see what happens if I unnaturally raise the exposure:

Overexposed Image - Blacks: 5

As you can see, the results doesn't mimic an on-camera overexposure. Darks and shadows are simply too dark. Part of this problem is how the Exposure control works in Lightroom 3 (it's significantly improved in Lightroom 4), but part of it is also the default Blacks settings. If you just set it to 0, here's the result:

Overexposed Image - Blacks: 0

The result is certainly more similar to what you'd expect. Keep in mind that this seriously underexposed image is used as an example, but you may experience similar problems with any sort of image with strong shadows, such as portraits of dark haired people or high contrast images such as the following:

High Contrast Image

I shoot RAW because I want to have full control and good working margins in post production. You'd better get used starting with neutral defaults rather than using a default contrast level, although moderate, introduced by Lightroom. In many cases, the default black clipping point is simply too much.

Development Process

As we've seen, Lightroom 4 uses more neutral defaults which, in my opinion, are a better starting point when you develop your images. Furthermore, the Lightroom 4 development process has been redesigned and, as a result, the control you've got on the tones of the image has been vastly improved.

Here's the Basic panel in Lightroom 3, showing the tools available in the 2010 development process whose functionality has been detailed in my Lightroom Tutorial:

Lightroom 3 - Basic Panel

On the other hand, here's the new Lightroom 4 Basic panel:

Lightroom 4 - Basic Panel

As you can see, in Lightroom 3, the tonal range is divided into 4 segments (Exposure, Recovery, Fill Lights and Blacks), while in Lightroom 4 it's divided into 5 (Exposure, Highlights, Shadows, Whites, Blacks). The differences, however, are much deeper and the way those sliders work has changed substantially.

Exposure

In Lightroom 3, the Exposure slider was used to control the overall exposure of the image but it had a major drawback: it ungracefully clipped the highlights. Here's what happens when raising the Exposure to +4 to the previous image:

Lightroom 3 - Exposure: +4

As you can see, highlights are completely blown up.

This is why a Brightness adjustment was available in Lightroom 3. Brightness modifies the exposure on the middle tones, without shifting (at least too much) the black and the white point. In Lightroom 3, tweaking the exposure could be tricky:

You would use the Exposure adjustment to set the overall exposure level, paying attention not to clip the whites too much.
You would use the Recovery adjustment to recover blown up details, if necessary.
You would use the Brightness slider to fix the exposure without affecting the white point.

Not difficult but time consuming. Also, images with strong highlights were even trickier to fix:

You cannot push Exposure too much, because you would clip the whites.
You could use Brightness, but it isn't effective on the shadows.
You could use Fill Lights to correct the exposure on the shadows, but large adjustments would shift up all of the histogram too, making it difficult to keep overall exposure under control.

In either case, the overall tones of the image would suffer, and you could end up with unnatural feelings or artificial-looking low contrast images. In my opinion, all the problems originate in how the basic tone adjustments end up affecting all of the histogram (with notable exception, such as Recovery).

Lightroom 4 has greatly improved these controls and now fixing the tones of your images is easier then ever. As you've surely noticed, the Brightness adjustment has disappeared. Indeed, the Exposure adjustment behaviour has changed dramatically: it now affects the middle tones with much less effect on blacks and whites. On the following image you can see which part of the histogram is mainly affected by the Exposure adjustment:

Lightroom 4 - Exposure

In fact, it falls off much more gracefully on either end of the histogram, mimicking the graceful degradation of film, rather than the abrupt clippings we experience with digital sensors. Here's the same image with a similar (excessive) Exposure adjustment:

Lightroom 4 - Exposure: +4

Much better. This way, applying an overall exposure adjustment as a starting point is much easier than before.

In this case, for example, a +.50 adjustment is a perfect starting point to develop this image, without worrying about blacks (yet):

Lightroom 4 - Exposure: +.50

Highlights and Shadows

As we've seen in the previous section, the Exposure adjustment now mainly affects middle tones, the central section of the histogram. In Lightroom 3, Exposure also affected a higher part of the histogram: this part is now more finely controlled by the Highlights adjustment:

Lightroom 4 - Highlights

Pretty much symmetrically, Lightroom 4 introduced another adjustment, called Shadows, to control the lower tones of the histogram:

Lightroom 4 - Shadows

You may think that Shadows is the equivalent of the legacy Fill Lights. It certainly is, if you only consider the tones it controls. But this is not only a mere name change, though. As we've seen with Exposure, in Lightroom 4 each tone adjustment affects contiguous tones to a lesser extent. This is very important, as you can now adjust different tones without a great impact on the all image.

Let's see what happens in Lightroom 3 if you raise the Fill Lights adjustment:

Lightroom 3 - Fill Lights: +80

Once more, this is an example meant to understand Lightroom's behaviour. Nonetheless, that's what happens if you push shadows too high in Lightroom 3. To tweak them correctly, you sometimes have to rely on local adjustments (with a brush) or, if possible, a careful and time-consuming adjustment of the entire tone curve. In fact, Fill Lights shifts the entire histogram up and down:

Lightroom 3 - Fill Lights: +80

Lightroom 4, on the other hand, applies a much more limited adjustment:

Lightroom 4 - Shadows: +100

The result is much more natural and, above all, predictable. Look at the resulting histogram, you can see how Shadows, although pushed up to the maximum value, has modified the histogram locally:

Lightroom 4 - Shadows: +100

As we go discovering the tone controls, we see that it's easier to get to the result we've got in mind using Lightroom 4 rather than Lightroom 3. In this case, I think an adjustment of Shadows +42 is what I'm looking for:

Lightroom 4 - Shadows: +42

Whites and Blacks

The last two tones adjustments, certainly not surprisingly, affects the lower and higher ends of the histogram and are basically used to set the white and the black point. Lightroom 3 only had an adjustment to set the black point (Blacks) and you had to set the white point using other controls (usually Exposure or a combination of Exposure and Recovery).

Lightroom 4 makes life easier (once more), and provide two separate controls to set your image clipping points: Whites and Blacks. In this case, once again, this controls affect a limited range of tones in the histogram and won't have a great impact on the overall tone range. As a result, these adjustment are more predictable and easier to use.

The behaviour of the Blacks adjustment in Lightroom 3, as you can see, was greater and spanned the overall histogram, even for moderate values:

Lightroom 3 - Blacks: +50

Please note how the histogram has been shifted down entirely:

Lightroom 3 - Blacks: +50

In Lightroom 4, on the other hand, the Blacks adjustment has a more limited and more local effect, even at maximum value:

Lightroom 4 - Blacks: +100

Look at the brightest parts of the image, such as the reflections on the water or the sky. That's the effect of not shifting down the entire histogram so much as Lightroom 3 did:

Lightroom 4 - Blacks: +100

The same thing happens with the Whites:

Lightroom 4 - Whites: +50

Adjusting the brightest parts of the image (the reflection of the lights) to make them brighter is very easy, without modifying the other tones. In Lightroom 3, this wasn't possible unless modifying the Exposure (and thus, the entire histogram), or modifying the tone curve.

Clarity

The Clarity adjustment has undergone a serious revision in Lightroom 4. It's now much more powerful and you can estimate using half the value you were using in Lightroom 3 to get pretty much the same effect.

Clarity is used to modify local contrast. This adjustment is very handy and potentially save many roundtrips from Lightroom to Photoshop during your workflow. However, I think that positive Clarity in Lightroom 3 had too much a weak effect in certain circumstances and I had to edit the image in Photoshop. Moreover, halos would appear very soon raising Clarity, and that's another issue that makes me open Photoshop more often than I'd like.

Both issue have been solved and Clarity works much better than ever in Lightroom 4.

This is an extreme example, but here's the result of applying maximum Clarity in both Lightroom 3 and 4:

Lightroom 3 - Clarity: +100

Lightroom 4 - Clarity: +100

It's too much for that image, I agree. But if you consider that you can locally brush in Clarity, this should give you an idea of the flexibility you can get from this improved adjustment.

Conclusion

So much for this post. We've seen how the new development process in Lightroom 4 is easier to grasp, easier to use and more predictable. Sure, we've got to "forget" about the old one and learn a new one from scratch. However, I think that the improvements are really worth this effort and I'm convinced that your effectiveness will improve dramatically.

Although out of scope in this post, here are other interesting new features and improvements that we will likely see in the upcoming Lightroom 4:

New Map module to manage geolocation data.
New Book module to make photo books.
New and improved local adjustment such as: Temperature and Tint and Noise reduction.

If you haven't done it yet, go to Adobe Labs, download and test drive Lightroom 4. I'm sure you'll be positively surprised.

Angle of View and Focal Length: A Rule of Thumb for a Quick Estimation

2012-01-17T14:31:00.000+01:00

Nowadays there are plenty of zooms lenses for any budget and many photographers aren't using big lens bags any longer. In fact, some lenses such as the Nikkon 18-200mm (in its various incarnation) are jack-of-all-trades that satisfy the needs of many photographers out there.

However, there's people who prefer carrying more lenses of different focal lengths and, possibly, better optical quality. I'm one of them. I'm not implying that the 18-200mm is a bad lens: it isn't. I simply made other choices.

Be it as it may, the point of this post is the following: you're framing a picture with your camera and you realize you need a longer lens to get the shot you've got in mind. The question is: Which focal length do I need?

More often than not, you're not carrying many lenses and the answer may be simple: the one you've got. Sometimes the estimate is easy, sometimes it is not. Imagine you're framing the shot with a 35mm and you deem it insufficient. Would a 100mm do the job? Or a 200mm? And what about a 300mm?

Other times you cannot even decide by trial and error: you haven't got any more lenses and you want to buy one. But you want to be sure beforehand.

You've probably experienced such a doubt. A common situation amongst novices with a telephoto lens is shooting the moon. You take your brand new 200mm lens (or whatever) and you frame the moon only to realize that your lens is way too short to get the amazing picture of the moon you wanted to take.

What focal length do I need?

Tradeoffs

Before getting deeper into the subject, let me tell you about some tradeoffs. They're obvious, but many people seem to miss them anyway:

Zoom with your feet.
Crop.

Zoom With Your Feet

The first advice I can give you is: zoom with your feet. This is the best tradeoff since it's got many advantages. Focal length is just one of the parameters and, sometimes, long lenses may prevent you from doing what a good photographer should do: walk around your subject, look for a good or an unusual point of view, change perspective and so on. The lens is a tool, it's up to you deciding how to use it.

There are times, however, when you can't get closer to your subject. There's no way to get closer to the moon on foot. There are ways to get closer to a leopard in the wild, but you aren't going to do it either. Other times you don't want a bird to see you and fly away. In this case, you do need a longer lens.

How long? Read on.

Crop

Nobody likes cropping: you've spent money on a good sensor and you want to squeeze any possible detail from it. I agree. However, it's better to crop a shot rather than lose it anyway. How much crop you can afford depends on what's the purpose of the image. If you just need a decent print, you can calculate beforehand how much crop you're willing to trade in for a better composition.

A 16 megapixel sensor, for example, gives an image almost 5000 pixels wide and more than 3000 pixel high (landscape frame). If you're going to print such image at 300 dpi, you're going to get approximately a 16" x 10" picture (42 cm x 27 cm). It's big, isn't it? If you crop it to half of its size, you're left with enough resolution to get a 8" x 5" picture (21 cm x 13.5 cm). Big enough for many uses.

Obviously, details aren't going to be as sharp as on the original image but it can be enough.

Look at this picture of the moon, for example:

200mm - Cropped to 2500x1600 pixels

It was taken using a 200mm lens and cropped down to approximately 2500x1600 pixels (scaled down further for inclusion in this blog).

It's not state of the art but still, some details of the craters are still visible.

However, this image, as whichever image you see in your viewfinder, can help you estimate the focal length you need to get the picture you'd like.

Angle of View

Here's some theory to answer this question. The angle of view can be calculated easily using the sensor (or film) size, the focal length of the lens and the distance to the subject. Since we're talking about telephoto lenses, we'll use a simpler model that simplifies a bit the maths and the resulting formula assuming that you're focusing at infinity (or sufficiently far away). This assumption holds in this case: we're talking about getting closer, hence it's safe to assume that we're pretty far away.

The maths tells us that the angle of view a of a given lens/sensor pair is:

a = 2 arctan(d/(2f))

where d is the sensor size and f is the focal length. The angle you're measuring (horizontal, vertical or diagonal) depends on how you measure the sensor size (horizontally, vertically or diagonally). As far as it concerns our estimation and the rule of thumb, it doesn't really matter.

Estimating the Required Focal Length

The previous formula tells us everything, doesn't it? Probably no, in fact, I admit it. We're photographers, not mathematicians. But a very useful rule of thumb comes directly from the properties of the previous equation. Let's plot it from 18mm to 600mm, using a sensor size of 23mm (the sensor size, as I told you, doesn't matter very much since it's effect is just stretching or expanding the function graph):

Angle of view from 18mm to 600mm

Let's ignore the y dimension and just focus on its shape. What can we infer? The shortest the focal length you're using (the closer you are to the origin), the steeper the curve. This is something you probably have observed when you zoom in with you telephoto lens: at the beginning, the effect of getting closer is more pronounced, and it slows down as you open your lens. Look how the angle gets smaller and smaller when zooming further at bigger focal length (arrows indicate the size of the angle of view reduction in focal length increments of 100mm, except the first one that is calculated from f=50mm approximately):

d(Angle of View)/d(focal length)

Ok, we knew that. What's next? This observation: look at the angle of view delta when scaling the focal length with a fixed multiplier. Let's use 2: the difference between 50, 100, 200 and 400 is very similar. Why? Once more, is a mathematical property of the arctan function. The plot of the arctan function is the following:

arctan(x), with x in [-2,2]

In the angle of view equation, f it's in the denominator: this means that when f increases, the arctan argument actually decreases. Look at the plot: if you consider an interval sufficiently near the origin, it very much resembles a line.

That's the trick in our rule of thumb! We're going to approximate the arctan function near the origin with the line y = x. Can we do it? Sure. Take a sensor size of d = 23mm. We're not interested in wider lenses, but even if we were, d/(2f) with f = 18mm gives 0.6. Pretty much into the linear zone of the function anyway. Here's the rule:

We can approximately affirm that, for sufficiently long lenses, multiplying the focal length by a factor of c reduces the angle of view by the same factor.

This is very handy, since you need to take no measurement. Just look into the viewfinder: want a moon twice as big? You need a focal length twice as big.

An Example

Take a look at the previous picture of the moon:

200mm - Cropped to 2500x1600 pixels (half the original width)

The moon size is approximately a quarter of the picture height. If I wanted to fill the frame, our rule of thumb tells us that I'd need approximately a 200mm · 4 = 800mm lens.

But the previous image is a crop: the original image is twice the size. That gives 1600mm, if I wanted to fill that frame.

Big bucks for the moon picture.

Next time you plan to buy a longer lens, frame a picture with your telephoto and use this rule.

P.S.: Plots were generated using the excellent Wolfram Alpha web application.

Nikon D5100 vs. Nikon D7000: My First Impressions

2012-01-15T14:52:00.000+01:00

I've been a happy owner of a Nikon D5100 for almost a year. Until last week. I decided to switch to the Nikon D7000 and, after just a few days, I'm compelled to write this blog post for others not to make my "mistake" and take an informed decision.

I want to be clear: the Nikon D5100 is an excellent DSLR camera for amateurs, and I'm sure it's a perfect choice for many amateurs photographers out there. In fact, it shares many important things with the D7000, its bigger sister: the very sensor itself and the image processor. As far as it concerns the image quality you're going to squeeze out of them, they're almost on par: the D7100 has a slightly wider dynamic range (13.9 EV vs 13.6 EV, a 2.2% difference) but so far I haven't succeeded in appreciating the difference.

Many differences between the two cameras are subtle, and many additional features you can find on the D7000 may be of no interest to you, such as the compatibility with older lenses without autofocus motor. On the contrary, some features of the D5100 that aren't available on the D7000 may be valuable to you: on-camera HDR, for example, is a big advantage if you want to shoot HDR photos without the hassle of a complex post-production workflow. I don't shoot HDR, but I recognize that many people do or may be interested in doing so.

If you're wondering about the differences, just Google for it: it's a hot topic. This post, for example, is an extensive yet very well summarized comparison table.

Why, then, did I decide to change it so soon? Basically, for a couple of reasons that are very important to me.

Ergonomics and Ease of Use (If You Shoot in Full Manual Mode)

I knew it, but I didn't bother investigating any further. And it was a major error. Ergonomics is important, as well as the organization of the camera controls, especially when it impairs the ability of shooting as quick as you'd like. I'm not a pro, but I'm an amateur that very often shoots in full manual mode. And when I'm not, I'm using Aperture priority mode and, in either case, I often need to tweak the camera settings from one shoot to another. The D5100 falls a bit short on this side and that's just where the D7000 shines.

Basically, when shooting with the D7000, I'm almost never entering the camera menu: just a "flick of a switch" and I'm done. The D7000 lets you change many parameters just using buttons and command dials, including the following:

Exposure compensation.
Flash compensation.
Release mode.
Metering mode.
Autofocus mode and autofocus area mode.
ISO sensitivity.
White balance.

The settings that are quickly accessible from a combination of a button and a dial are the great majority you usually need. Moreover, the D7000 offers two additional mechanisms to quickly speed up the camera tuning:

Two user modes (U1 and U2), that let you save entire banks of camera settings and just recall them using the mode dial.
My Menu: you can build a custom menu and populate it with your favorite menu settings.

That's almost everything I need when shooting outside a controlled environment. The ergonomics is very well thought of: you quickly get used to the camera buttons and their position and in no time you find yourself tweaking many parameters without leaving the viewfinder. That's a major win against the D5100, for which you've got to resort to the camera menu for many of those parameters.

With the D5100 I lost some shots because I hadn't got sufficient time to setup the camera. With the D7000, this problem is greatly mitigated. And your subjects won't get bored when you fiddle with your camera, staring at its screen.

Focus

My first impressions confirms that the D7000 focus system is way ahead,when compared to the D5100's one. First of all, the D7000 offers 39 focus points, 9 of which are cross-type, against the 11 ones offered by the D5100, of which only 1 is cross-type. But the number of focus points isn't just the only important metric. I tried, although not yet thoroughly, to compare the behaviour of the two focus systems when tracking moving subjects and I've got the clear impression that the D7000 is much faster and more precise than the D5100. Both focus systems have their limits and may experience difficulties in certain conditions: but in the same situation (and, of course, with the same lens), I find the D7000 a lot faster.

This fact, along with the fact that the autofocus mode and the autofocus area mode can be configured with the dials, guarantee that the D7000 provides a smoother overall experience when shooting, focussing and tweaking the camera settings.

Conclusion

These two factors influenced my decision making and I finally changed my D5100 with a new D7000. Everyone's got its own needs and priorities and, in my case, the possibility of using the camera in full manual mode with such a great improvement in terms of speed and effectiveness was crucial.

Obviously, I'm benefitting from the additional features of the D7000, but the thing I really missed was its ease of use.

If you've got the same doubts, if you're experiencing the same troubles, or if you think you'll take real advantage of some of its distinctive features, give the D7000 a try. If you're happy with the D5100, think twice before switching and investing more money on a new camera. A better lens instead of a better camera could be a wiser choice.

Adobe Photoshop Lightroom Tutorial - Part XVII - Tone Curve

2012-01-08T13:43:00.002+01:00

Part I - Index and Introduction

Introduction: Adobe Camera RAW Do's and Don'ts

So far, we've been dealing with Lightroom's basic develop tools and we've seen how the tonal scale of an image can be flexibly tweaked relying only on these tools.

Nevertheless, it's important to understand that most of those tools are provided by Adobe Camera RAW, running within Lightroom under the hood, and you may think of them as of your digital darkroom. More often than not I see people stuck with Camera RAW controls while trying to get the picture they want but, sadly, without success. Some beginners fail to realize the purpose of Camera RAW.

This is important: read carefully on.

Adobe Camera RAW it's the engine that reads and interprets RAW files to produce a final image that can be processed by an image editing tool such as Photoshop or Lightroom. To put it in another way, Camera RAW is the bridge between you and the proprietary format of the RAW file produced by your camera sensor. That's why Adobe ships Camera RAW inside those programs: in order for photographers to seamlessly manage their RAW files without a workflow disruption. You don't have to rely to an external program (such the one that comes with your camera) to produce an image from your RAW files: the develop stage is just part of the workflow and you do it seamlessly inside Lightroom (and in Photoshop to a lesser extent).

For this reason, you should consider Camera RAW develop controls the starting point of your develop workflow and be aware of their purpose, drawbacks and limitations.

The purpose of shooting RAW and using a raw processor such as Camera RAW is simply taking advantage of the additional information gathered by your camera sensor. In fact, it's during the develop stage when you take full advantage of it: Adobe Camera RAW uses the information found on RAW files to produce the final image according to the parameters you've set. When you set the white and the black point of an image using tonal scale controls such as exposure, recovery and blacks, Camera RAW uses the data of your sensor to produce the final image. Since sensors can have very high dynamic ranges (13 stops are common nowadays), you can use those information to produce a faithful resulting image even if you're applying strong exposure corrections, even in the 1-stop range or more. Depending on your sensor dynamic range, you will be able to get more details from the shadows when you're raising the exposure, or more details in the highlights when you're lowering it. It all boils down to what we've explained more extensively in previous posts: you should always shoot RAW.

The drawbacks and the limitations of this tool come from its own definition: it's a tool meant to develop a RAW file to produce an image to be fed to an image editing tool. Don't expect Camera RAW to be the swiss-army knife for tonal adjustment during your workflow, that's a responsibility of the image editing tool you're using. Lightroom comes with additional tools to tweak the tones of an image and we'll explore them in this post.

Why Tone Reproduction Is Difficult

This is an introductory section about tone reproduction issues and dynamic range of some common mediums used by photographers. You can skip this section if these concepts are already known to you. As a more detailed introduction about the concepts used hereon, you can read this post: "Tones and Dynamic Range. Why You Should Shoot RAW".

The human eye has a very high dynamic range, much higher than your camera sensor (at least nowadays): it's an estimated 30 f-stops. But the physics of the human eye is very different than the physics of a sensor: the eye cannot see very distant luminance values at the same time since it needs some "adjustment time". You're surely are aware of if: try to go out on a sunny day and fix your attention to a very dark spot. You will be able to see details in the shadow as well as you can in the bright, but not at the same time.

The problem with camera sensors is that, when you take a photo, you're recording sensor data in a given instant of time. That's the reason why you simply cannot have satisfactory sensor reading of a scene whose dynamic range is bigger than your sensor's. That's also why techniques such as HDR were invented: multiple exposures are taken to faithfully record data of very different parts of an image (luminance-wise) and then blend them together.

This problem is effectively worsened when you consider other mediums you use during your workflow whose dynamic range is nowhere near to the theoretical value you need, such as your monitor or your printer.

To solve this problem, you "fix" tones in your image to give a "proper", although subjective, luminance value to different zones of your image. In fact, many steps in a photographer's workflow may involve non-linear tone mapping functions. As an example, think about gamma correction: it's a non-linear transformation meant to adjust luminance output taking into account the physics of the human eye.

Tone Curve

Lightroom, as well as most image editing programs, offer a tool that let you modify such tone mapping function: it's usually called the tone curve, or simply curves.

Lightroom Develop Module - Tone Curve Panel

This tool is found into the Tone Curve panel of Lightroom's Develop module. In the upper part of the image you can see a graph that has the following characteristics:

The x-axis represent the original tone value of the image from black to white (the input value).
The y-axis represent the modified tone value of the image from black to white (the output value, what we get on the picture).
The current image histogram in the background.
The mapping function plotted in white above the histogram.

An identical transformation (in which case no modification is applied) is represented by the y = x equation, which is plotted a straight line from the origin of the graph to the upper right corner. The typical S-curve used by default by Lightroom and shown in the previous picture adds some contrast to your image: dark tones are mapped to darker ones (y < x), the middle tones doesn't get remapped (y = x) and light tones are mapped to lighter ones (y > x).

You can tweak the mapping function to remap a specific tone value to another one in a variety of ways:

Applying adjustments to the Region sliders.
Applying free-hand transformation to the curve.
Using the adjust tone tool and dragging the mouse over the part of the image you want to change.

If, for example, you want to darken the shadows, you'll modify the curve so that the S curve is more pronounced on darker tones:

Tone Curve - Darkening Shadows

Sliders are an intuitive way to modify the tone curve and use the same naming conventions and histogram subdivisions we've seen on basic tone controls:

Highlights, roughly corresponding to the zone affected by the Recovery tool.
Lights, roughly corresponding to the zone affected by the Exposure tool.
Darks, roughly corresponding to the zone affected by Fill Lights tool.
Shadows, roughly corresponding to the zone affected by Blacks tool.

You are not limited to using the Region sliders or applying monotonic transformations, though. If you need to apply more complex tone transformation functions, you can switch to the free-hand transformation mode (using the small graph icon on the bottom right corner of the panel) to add and drag control points on the mapping function according to your needs:

Tone Curve - Custom Curve

Also, if you want to modify the mapping of a specific tone in your photo, you can use the following procedure:

Grab the Adjust Tone Curve tool, clicking on the small circular icon on the left of the graph: your mouse pointer will change to a cross with a slider control.
Click on the point of the image whose tone you want to change.
Keep the mouse clicked and drag upwards or downwards to raise or lower the mapping for that tone.

Why This Duality?

At the beginning it may seem to you that the Tone Curve tool sort of duplicates the functionality of the basic tone controls we've seen in the Basic tools.

To answer this question with a quick "No", is sufficient to note that basic tone tools won't allow for non monotonic transformation to be applied. You can tweak each region of the histogram, but the side effect will always be a monotonic transformation.

There are is a difference that is even more important to grasp: the tone mapping curve only maps the currently displayed tones. On the other hand, when "developing" a photo with Camera RAW you are able to effectively choose which tones will end up in your photo, moving the entire histogram up and down, and using additional data from your RAW file. That means that the effect of a mapping curve on the clipping points is much more limited than what you can achieve using Camera RAW tone tools.

The latter can be used, as we know, to recover blown out data in the highlights or details from the shadows. The former simply remaps the information that's available at the moment, that is, the image produced by Camera RAW.

In the following section we'll see an example of this effect to help you understand when to use one tool or the other.

An Example Image

Some days ago I entered, almost by chance, Amsterdam's Openbare Bibliotheek and I was captivated by the incredible light that was in there. The building is entirely white and there's a strong, diffused, soft white light throughout the library. I soon decided to take some shots. This is one of the final images:

Amsterdam's Openbare Bibliotheek

This is a classical example of the tone reproduction problem we were talking about in the first sections of this post: the human eye is very good at quickly jumping from one zone to another with very different luminance levels but recording this on a camera sensor is a tough problem. The scene in question, in fact, is a scene whose tone cannot be reproduced either without being remapping or being clipped. In fact, the resulting image is the result of a specific process whose goal was to maximize the luminance of the environmental lights while preserving the "correct" exposure of the darker zone (such as the floor): in practice, this was achieved "squeezing" the luminance information into the histogram taking care to maintain a natural contrast between darker and lighter zones.

Taking the Picture

The first step obviously was taking the picture. You have already learnt that more often than you'd like you've got to come to a compromise when adjusting your image exposure. In this case, being a strongly lit environment, I decided to give preference to highlight preservation, despite looking for a high key image.

Since I know that my camera meter was going to be fooled by that lightning condition, I manually underexposed the image by 1.5 f-stops, to be sure not to completely burn out the highlights, double checking this with the on-camera histogram. The result was this:

Original Image - Highlights preserved

This is a conservative approach: in my mind I already knew that I wanted a high key image and I could have accepted some clipping on the highlights. But if you clip a channel, that information is gone forever, and we don't want that: sometimes, you may envision a different use for a picture in post-production. Moreover, in this case, I haven't lost details in the shadows even if the image is strongly underexposed. And even if I had, I knew that I could recover much of them using additional data from my camera sensor: over time I learnt that my sensor allows for recovering shadow details when underexposed more than a 1-stop and, in this case, I was underexposing in that range.

Of course, every camera is different and you've got to know yours when assessing the lightning conditions and taking a decision and remember: there are times when you simply cannot record all of a scene's dynamic range and you'll have to make a choice. The camera histogram will help you check that the result is what you want. If you're unsure, bracket the exposure instead of losing a good shot.

Basic Image Development

The first step in the workflow is "developing" the RAW file to produce a suitable image, as explained so far in the previous parts of this tutorial. The first step was correcting the white balance and the tint: as you can see in the original image, it's pretty warmer than it should be. My camera wasn't calibrated for that lightning condition nor was I using a grey card. However, there's plenty of white in the picture to use Lightroom's White Balance Selector to fix that.

White Balance Correction

The second step was setting the initial tone settings for the image. I raise the exposure by 1.55 f-stops and checked the highlights:

Exposure: +1.55

This is where we are going to see a fundamental difference between basic tonal settings (from Camera RAW) and tone curve adjustment. Look at the difference between the previous image and the image we want to get: the previous image is still much darker, especially in the white zones in the roof. The floor, however, is correctly exposed. We could try and boost the exposure:

Exposure: +2.50

Now, the roof is as exposed as I'd like but, obviously, the bottom half of the image is really washed out. Remember that this is subjective: I want strong lights in the roof, but correct exposure in the floor. If I wanted a higher key image, I'd probably raise exposure a little bit more. If you feel it's right to push exposure further, go on: it all depends on the result you want to achieve.

How could we fix that using basic tone controls? Well, the only way of pushing information back on the dark side of the histogram is raising the blacks:

Blacks: 13

As soon as we begin raising the blacks, we notice that two things happen: the contrast and the color saturation rise as well. Why? Because rising the blacks stretches the histogram left and discards information that goes beyond the black point. You end up with a subset of the original data stretched throughout the histogram. It's a good technique to create a punchy sunset, but that's not we want in this case. Look at some dark zone even with a very moderate increase of the blacks:

Detail

The shadows in the floor are exaggeratedly deep. That's the effect of raising the black: you're effectively establishing where the black point is and information below it is discarded.

That's why, in this case, we're going to use a tone mapping curve instead. Basic tone controls are used to generate a picture form the RAW: in this case, we set the overall exposure of the image to a suitable level. and we cannot go further. From here on, we're going to rely on tone curves for additional editing instead.

Adjusting the Tone Curve

Now that we've got a suitable image to edit, all we want is: raising the lights. Let's adjust the curve until we're happy with it and we end up with the final image we've seen at the beginning of this post:

Final Image

The adjustment used to get the final image is the following:

Tone Curve Adjustment - Lights: +57, Highlights: +8

The curve is an S-shape more pronounced on the right part of the histogram. Its effect is lightening the tones from the darks zone upwards (where y > x) and the bigger x, the more pronounced its effect, since the difference (y - x) gets increasingly bigger.

A Much Higher Key

Although this is not a suitable image for this kind of mood, let's see how you could achieve a "stairway to heaven" effect with a custom curve. Pushing lights further and reducing highlights to preserve some details gives us the following result:

Higher Key Image

The corresponding tone curve is the following:

Tone Curve Adjustment - Lights: +100, Highlights: -86

Conclusion

Curves are a powerful tool to customize the representation of tones in your image and, because of the very nature of the human eyes and of our camera sensors, they are a fundamental part of a photographer's everyday workflow. They may seem intimidating to the novice but they're pretty intuitive once you understand their principle of operation.

Also, tone curves are complementary to basic (Camera RAW) tone controls and it's important you understand and master both to achieve the results you want.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

Adobe Photoshop Lightroom Tutorial - Part XV - Speeding Up Your Workflow Using Presets and the Painter Tool

2012-01-04T00:35:00.006+01:00

Part I - Index and Introduction
Part XVI - Saving And Migrating Your Adobe Lightroom Presets

In previous parts of this series we've already seen how Lightroom lets you save a set of configuration options into a reusable entity. In Part XIII and Part XIV, for example, we've used two adjustment brushes to improve both the iris and the sclera (the eye white) of our model. As you've seen, you can save the definition of a brush and reuse it whenever you need it.

In this part, we will see how we can use a similar technique to speed up and greatly simplify your workflow when using Lightroom presets.

What a Preset Is

A preset is a set of configurations that can bulk-applied to a group of photos at a time, which is something you find yourself doing more often than not. Lightroom let you define two kinds of presets:

Develop preset.
Metadata presets.

As their names imply, a develop preset is a set of develop configuration options and a metadata preset is a set of metadata values such as EXIF and IPTC metadata. In both cases, Lightroom lets you specify a value for every option available in the corresponding set. If you're defining a develop preset, for example, you will be able to specify the value for each and every option that you find in the Develop module.

Every time you find yourself during repetitive work it's a good opportunity to consider creating a preset. Common situations in which you can take advantage of a preset are, for example:

Adding location, contact or copyright metadata.
Applying the same basic tone adjustment to a set of photos taken under the same exposure condition.
Applying the same color temperature and tint adjustment to a set of photos taken under the same lightning conditions.
Applying the same lens correction parameters to a set of photos taken with the same lens.
Applying the same camera calibration parameters to a set of photos taken with the same lightning conditions.

How To Create a Develop Preset

To create a develop preset, you have to follow the following steps:

Open a photo in the Develop module.
Apply the settings you want to save in a preset. During this step you can safely ignore the values for the options you don't want to include in the new preset.
Select the Develop/New Preset… menu item or click the "+" button in the upper right corner of the Presets panel, as shown in the following image.

Develop Module - Detail of the Presets Panel

Lightroom will show you the New Develop Preset window.

New Develop Preset Window

Introduce a name for your new preset.
Choose the folder where you want to store your preset. By default, Lightroom suggests you use the User Presets folder but you may create a folder hierarchy using the Develop/New Preset Folder… menu item or the New Folder… item in the Folder listbox of the New Develop Preset window.
Choose the settings you want to save in your preset. In the previous image, for example, we've chose the Noise Reduction settings, the Lens Corrections settings and the camera Calibration settings because we want to automate this corrections for a set of photos taken to the same subject in a single session with the same camera, the same lens, the same ISO sensibility and the same lightning conditions.
Select the Create button to create the new preset.

Once you've created a new preset, it will appear in the presets hierarchy shown into the Presets panel of the Develop module.

How To Create a Metadata Preset

The steps you need to follow to create a metadata preset are conceptually very similar to those required to create a develop preset: you need to customize the metadata of a photo and use it to create a new metadata preset. The procedure is the following:

Choose a photo in the Library module.
Apply the metadata you want to save in a preset. During this step you can safely ignore the value for the metadata key you don't want to include in the new preset.
Select the Metadata/Edit Metadata Presets… menu item or the Edit Preset… item in the Preset listbox at the top of the Metadata panel (shown in the following picture).

Library Module - Detail of the Metadata Panel

Lightroom will show you the Edit Metadata Presets window.

Edit Metadata Presets Window

Check the metadata keys you want to include in the new preset.
Select the Save Current Settings As New Presets… item in the Preset listbox at the top of the window and introduce a name for the new preset.

Once you've created a new metadata preset, it will appear in the Preset listbox in the Metadata panel.

Using Presets

Presets can be used in a variety of way, depending on the stage of your workflow you're in.

In the Library module, you can apply presets in three ways:

You can select one or more photos, right-click on them and choose the preset you want to apply from the Develop Settings or from the Metadata Presets submenus. Be aware that Lightroom will show user defined presets at the bottom of the submenus. If you've got plenty of them, don't panic: there they are, but you will have to scroll the entire submenu down. While this is pretty easy on a Mac, it is a pretty clumsy procedure on Windows.
You can choose the metadata preset you want to apply from the Preset listbox in the Metadata panel.
You can use the Painter tool (which is found in the toolbar, see Part II of this tutorial) to paint a preset on the photos you choose. If you can't find the toolbar, enable it using the View/Toolbar menu item or directly select the Painter tool using the Metadata/Enable Painting menu item.

You will choose the most suitable method depending on the situation. If, for example, you need to apply a preset to all of the photos in a folder or to a large set of easily selectable photos, choosing them all and right clicking on them is surely the quicker way to do it. If, on the other hand, you're reviewing your photos one by one in the Library grid view, the Painter tool will be more appropriate than an infinite series of right clicks.

Using The Painter Tool

The painter tool, although somewhat hidden, is a pretty powerful tool that will let you "spray" not only presets, but a larger set of adjustments over a photo. In the current Lightroom release (v. 3), the painter tool lets you apply the following kind of adjustment to a photo:

Keywords.
Label.
Flag.
Rating.
Metadata.
Settings.
Rotation.
Target Collection.

This tool is very handy when you're reviewing your photos on the Library grid view in whichever stage of your workflow. Sometimes, you will use it at the beginning, for example to fix an incorrect rotation of some photos or to apply some metadata preset. Other times, you will use it at the end, during the rating process. By its own nature, it's very easy to use: just pick up an adjustment to apply, and keep on clicking on the photos you want to modify.

To activate the painter tool you can click on the "spray" icon on the toolbar, as shown in the following picture:

Toolbar - Painter tool (Highlighted in Red)

Once the painter tool is activated, your mouse pointer will change to the spray icon shown above and the toolbar section of the painter tool will expand to make place to other controls that will appear. The first one of these controls is a listbox that lets you choose the kind of adjustment you want to apply. The complete list of available adjustments is provided at the beginning of this section. The other controls are contextual and will depend on the kind of adjustment you choose, as shown in the following pictures.

Painter - Develop Presets

Painter - Keywords

Painter - Rating

As you can see in the first of the previous pictures, you can use the Painter tool to choose a preset, in this case a develop preset, and apply to every photo you click.

When you're finished painting, just dismiss the painter tool pressing the Esc key or clicking once again on the Painter tool in the toolbar.

Applying Presets During Import

So far we've seen how presets can enhance your Lightroom experience by speeding up any phase of your daily workflow. Sometimes, however, presets can be useful even before your photos have entered your Lightroom catalog. During the import phase, Lightroom will give the option of:

Applying a develop preset.
Applying a metadata preset.
Applying a set of keywords.

This is handy when the set of photos you're importing share common characteristics and you can apply the corresponding presets while importing them into the catalog. I always use this option to:

Apply basic metadata, such ownership, location and copyright.
Apply camera calibration settings.
Apply lens correction settings.
Apply noise correction settings.

Let's suppose you're importing a set of photos from a portrait session. Based on your experience, you know you can take advantage of bulk-applying the following presets:

A specific clarity adjustment (maybe slightly negative).
A specific camera calibration setting, such as Camera Portrait or a custom one of yours.
The lens correction profile for your lens.
A set of keywords.
Additional IPTC metadata of your session (model, location, etc.)

During the import, Lightroom will apply the presets you chose and then you'll begin working on the already adjusted photos.

In the following picture you can see a detail of the Import window, the Apply During Import panel.

Import Window - Apply During Import Panel

As you can see, this panel lets you choose a develop preset, using the Develop Settings listbox, a metadata preset, using the Metadata listbox, and a set of keywords, typing them into the Keywords text box.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

Google Authenticator: Using It With Your Own Java Authentication Server

2011-12-21T18:07:00.000+01:00

The Google Authenticator application for mobile devices is a very handy application that implements the TOTP algorithm (specified in RFC 6238). Using Google Authenticator you can generate time passwords that can be used to authorize users in an authentication server that shares the secret key of the requesting users.

Google Authenticator is mainly used to access Google services using two-factor authentication. However, you can take advantage of Google Authenticator to generate time based password to be authenticated by a server of yours. The implementation of such a server is pretty simple in Java and you can get some inspiration getting the source code of the Google Authenticator PAM module. In this blog post, we will go through a simple implementation of the TOTP algorithm in a Java class.

Generating the Secret Key.

To generate the secret key we will use a random number generator to fill up a byte array of the required size. In this case, we want:

A 16 characters Base32 encoded secret key: since Base32 encoding of x bytes generate 8x/5 characters, we will use 10 bytes for the secret key.
Some scratch codes (using Google's jargon).

// Allocating the buffer

byte[] buffer =

new byte[secretSize + numOfScratchCodes * scratchCodeSie];

// Filling the buffer with random numbers.

// Notice: you want to reuse the same random generator

// while generating larger random number sequences.

new Random().nextBytes(buffer);

Now we want to extract the bytes corresponding to the secret key and encode it using the Base32 encoding. I'm using the Apache Common Codec library to get a codec implementation:

// Getting the key and converting it to Base32

Base32 codec = new Base32();

byte[] secretKey = Arrays.copyOf(buffer, secretSize);

byte[] bEncodedKey = codec.encode(secretKey);

String encodedKey = new String(bEncodedKey);

Loading the Key Into Google Authenticator

You can manually load the key into Google Authenticator, or generate a QR barcode to have the application loading it from it. If you want to generate a QR barcode using Google services, you can generate the corresponding URL with a code such as this:

public static String getQRBarcodeURL(
String user,
String host,
String secret) {
String format = "https://www.google.com/chart?chs=200x200&chld=M%%7C0&cht=qr&chl=otpauth://totp/%s@%s%%3Fsecret%%3D%s";
return String.format(format, user, host, secret);
}

Verifying a Code

Now that we've generated the key and our users can load them into their Google Authenticator application, we need the code required to verify the generated verification codes. Here's a Java implementation of the algorithm specified in the RFC 6238:

private static boolean check_code(
String secret,
long code,
long t)
throws NoSuchAlgorithmException,
InvalidKeyException {
Base32 codec = new Base32();
byte[] decodedKey = codec.decode(secret);

// Window is used to check codes generated in the near past.
// You can use this value to tune how far you're willing to go.
int window = 3;
for (int i = -window; i <= window; ++i) {
long hash = verify_code(decodedKey, t + i);

if (hash == code) {
return true;
}
}

// The validation code is invalid.
return false;
}

private static int verify_code(
byte[] key,
long t)
throws NoSuchAlgorithmException,
InvalidKeyException {
byte[] data = new byte[8];
long value = t;
for (int i = 8; i-- > 0; value >>>= 8) {
data[i] = (byte) value;
}

SecretKeySpec signKey = new SecretKeySpec(key, "HmacSHA1");
Mac mac = Mac.getInstance("HmacSHA1");
mac.init(signKey);
byte[] hash = mac.doFinal(data);

int offset = hash[20 - 1] & 0xF;

// We're using a long because Java hasn't got unsigned int.
long truncatedHash = 0;
for (int i = 0; i < 4; ++i) {
truncatedHash <<= 8;
// We are dealing with signed bytes:
// we just keep the first byte.
truncatedHash |= (hash[offset + i] & 0xFF);
}

truncatedHash &= 0x7FFFFFFF;
truncatedHash %= 1000000;

return (int) truncatedHash;
}

Conclusion

You can now use the Google Authenticator applications and use it to generate time based passwords for your users, authenticated against your own authentication server.

As you can see, the required code is pretty simple and all of the required cryptographic functions are provided by the runtime itself. The only nuisance is dealing with signed types in Java.

Enjoy!

Using a ThreadPoolExecutor to Parallelize Independent Single-Threaded Tasks

2011-12-16T21:29:00.005+01:00

The task execution framework, introduced in Java SE 5.0, is a giant leap forward to simplify the design and the development of multi threaded applications. The framework provides facilities to manage the concept of task, to manage thread life cycles and their execution policy.

In this blog post we'll describe the power, the flexibility and the simplicity of this framework showing off a simple use case.

The Basics

The executor framework introduces an interface to manage task execution: Executor. Executor is the interface you use to submit tasks, represented as Runnable instances. This interface also isolates a task submission from a task execution: executors with different execution policies all publish the same submission interface: should you change your execution policy, your submission logic wouldn't be affected by the change.

If you want to submit a Runnable instance for execution, it's as simple as:

Executor exec = …;
exec.execute(runnable);

Thread Pools

As outlined in the previous section, how the executor is going to execute your runnable isn't specified by the Executor contract: it depends on the specific type of executor you're using. The framework provides some different types of executors, each one with a specific execution policy tailored for different use cases.

The most common type of executors you'll be dealing with are thread pool executors., which are instances of the ThreadPoolExecutor class (and its subclasses). Thread pool executors manage a thread pool, that is the pool of worker threads that's going to execute the tasks, and a work queue.

You surely have seen the concept of pool in other technologies. The primary advantage of using a pool is reducing the overhead of resources creation, reusing structures (in this case, threads) that have been released after use. Another implicit advantage of using a pool is the capability of sizing your resource usage: you can tune the thread pool sizes to achieve the load you desire, without jeopardizing system resources.

The framework provides a factory class for thread pools called Executors. Using this factory you'll be able to create thread pools of different characteristics. Often, the underlying implementation is often the same (ThreadPoolExecutor) but the factory class helps you quickly configure a thread pool without using its more complex constructor. The factory methods are:

newFixedThreadPool: this method returns a thread pool whose maximum size is fixed. It will create new threads as needed up to the maximum configured size. When the number of threads hits the maximum, the thread pool will maintain the size constant.
newCachedThreadPool: this method returns an unbounded thread pool, that is a thread pool without a maximum size. However, this kind of thread pool will tear down unused thread when the load reduces.
newSingleThreadedExecutor: this method returns an executor that guarantees that tasks will be executed in a single thread.
newScheduledThreadPool: this method returns a fixed size thread pool that supports delayed and timed task execution.

This is just the beginning. Executors also provide other facilities that are out of scope in this tutorial and that I strongly encourage you to study about:

Life cycle management methods, declared by the ExecutorService interface (such as shutdown() and awaitTermination()).
Completion services to poll for a task status and retrieve its return value, if applicable.

The ExecutorService interface is particularly important since it provides a way to shutdown a thread pool, which is something you almost surely want to be able to do cleanly. Fortunately, the ExecutorService interface is pretty simple and self-explanatory and I recommend you study its JavaDoc thoroughly.

Basically, you send a shutdown() message to an ExecutorService, after which it won't accept new submitted tasks, but will continue processing the already enqueued jobs. You can pool for an executor service's termination status with isTerminated(), or wait until termination using the awaitTermination(…) method. The awaitTermination method won't wait forever, though: you'll have to pass the maximum wait timeout as a parameter.

Warning: a source of errors and confusion is a understanding why a JVM process never exits. If you don't shutdown your executor services, thus tearing down the underlying threads, the JVM will never exit: a JVM exits when its last non-daemon thread exits.

Configuring a ThreadPoolExecutor

If you decide to create a ThreadPoolExecutor manually instead of using the Executors factory class, you will need to create and configure one using one of its constructors. The most extensive constructor of this class is:

public ThreadPoolExecutor(
int corePoolSize,
int maxPoolSize,
long keepAlive,
TimeUnit unit,
BlockingQueue<Runnable> workQueue,
RejectedExecutionHandler handler);

As you can see, you can configure:

The core pool size (the size the thread pool will try to stick with).
The maximum pool size.
The keep alive time, which is a time after which an idle thread is eligible for being torn down.
The work queue to hold tasks awaiting execution.
The policy to apply when a task submission is rejected.

Limiting the Number of Queued Tasks

Limiting the number of concurrent tasks being executing, sizing your thread pool, represents a huge benefit for your application and its execution environment in terms of predictability and stability: an unbounded thread creation will eventually exhaust the runtime resources and your application might experience as a consequence, serious performance problems that may lead even to application instability.

That's a solution to just one part of the problem: you're capping the number of tasks being executed but aren't capping the number of jobs that can be submitted and enqueued for later execution. The application will experience resource shortage later, but it will eventually experience it if the submission rate consistently outgrows the execution rate.

The solution to this problem is:

Providing a blocking queue to the executor to hold the awaiting tasks. In the case the queue fills up, the submitted task will be "rejected".
The RejectedExecutionHandler is invoked when a task submission is rejected, and that's why the verb rejected was quoted in the previous item. You can implement your own rejection policy or use one of the built-in policies provided by the framework.

The default rejection policies has the executor throw a RejectedExecutionException. However, other built-in policies let you:

Discard a job silently.
Discard the oldest job and try to resubmit the last one.
Execute the rejected task on the caller's thread.

When and why would one use such a thread pool configuration? Let's see an example.

An Example: Parallelizing Independent Single-Threaded Tasks

Recently, I was called to solve a problem with an old job my client was running since a long time ago. Basically, the job is made up of a component that awaits for file system events on a set of directory hierarchies.Whenever an event is fired, a file must be processed.The file processing is performed by a proprietary single threaded process. Truth be said, by its own nature, even if I could, I don't if I could parallelize it. The arrival rate of events is very high throughout part of the day and there's no need to process file in real time, they just to get processed before the next day.

The current implementation was a mix and match of technologies, including a UNIX shell script that was responsible for scanning huge directory hierarchies to detect where changes were applied.When that implementation was put in place, the number of cores in the execution environment were two, as much. Also, the rate of events was pretty lower: nowadays they're in the order of the millions, for a total of between 1 and 2 terabytes of raw data to be processed.

The servers the client is running these processes nowadays are twelve core machines: a huge opportunity to parallelize those old single-threaded tasks.We've got basically all of the ingredients for the recipe, we just need to decide how to build and tune it.Some thoughts before writing any code were necessary to understand the nature of the load and these are the constraints I detected:

A really huge number of files is to be scanned periodically: each directory contains between one and two millions of files.
The scanning algorithm is very quick and can be parallelized.
Processing a file will take at least 1 second, with spikes of even 2 or 3 seconds.
When processing a file, there is no other bottleneck than CPU.
CPU usage must be tunable, in order to use a different load profile depending on the time of the day.

I'll thus need a thread pool whose size is determined by the load profile active at the moment of invoking the process. I'm inclined to create, then, a fixed size thread pool executor configured according to the load policy.Since a processing thread is only CPU-bound, its core usage is 100% and waits on no other resources, the load policy is very easy to calculate: just take the number of core available in the processing environment and scale it down using the load factor that's active at that moment (and check that at least one core is used in the moment of peak):

int cpus = Runtime.getRuntime().availableProcessors();
int maxThreads = cpus * scaleFactor;
maxThreads = (maxThreads > 0 ? maxThreads : 1);

Then, I need to create a ThreadPoolExecutor using a blocking queue to bound the number of submitted tasks. Why? Well: the directory scanning algorithms are very quick and will generate a huge number of files to process very quickly. How huge? It's hard to predict and its variability is pretty high. I'm not going to let the internal queue of my executor fill up indiscriminately with the objects representing my tasks (which include a pretty huge file descriptor). I'll prefer let the executor reject the files when the queue fills up.

Also, I'll use the ThreadPoolExecutor.CallerRunsPolicy as rejection policy. Why? Well, because when the queue is filled up and while the threads in the pools are busy processing the file, I'll have the thread that is submitting the task executing it. This way, the scanning stops to process a file and will resume scanning as soon as it finishes executing the current task.

Here's the code that creates the executor:

ExecutorService executorService =
new ThreadPoolExecutor(
maxThreads, // core thread pool size
maxThreads, // maximum thread pool size
1, // time to wait before resizing pool
TimeUnit.MINUTES,
new ArrayBlockingQueue<Runnable>(maxThreads, true),
new ThreadPoolExecutor.CallerRunsPolicy());

The skeleton of the code is the following (greatly simplified):

// scanning loop: fake scanning
while (!dirsToProcess.isEmpty()) {
File currentDir = dirsToProcess.pop();

// listing children
File[] children = currentDir.listFiles();

// processing children
for (final File currentFile : children) {
// if it's a directory, defer processing
if (currentFile.isDirectory()) {
dirsToProcess.add(currentFile);
continue;
}

executorService.submit(new Runnable() {
@Override
public void run() {
try {
// if it's a file, process it
new ConvertTask(currentFile).perform();
} catch (Exception ex) {
// error management logic
}
}
});
}

// ...

// wait for all of the executor threads to finish
executorService.shutdown();

try {
if (!executorService.awaitTermination(60, TimeUnit.SECONDS)) {
// pool didn't terminate after the first try
executorService.shutdownNow();
}

if (!executorService.awaitTermination(60, TimeUnit.SECONDS)) {
// pool didn't terminate after the second try
}
} catch (InterruptedException ex) {
executorService.shutdownNow();
Thread.currentThread().interrupt();
}

Conclusion

As you can see, the Java concurrency API is very easy to use, very flexible and extremely powerful. Some years ago, I would have taken much more effort to write such a simple program. This way, I could quickly solve a scalability problem caused by a legacy single threaded component in a matter of hours.

Hyperfocal Distance: Advanced Depth of Field and Focusing Tips

2011-12-14T20:46:00.001+01:00

The Basics: Depth of Field

Focusing is invariably one of the tasks you perform while taking a shot. You also know that focusing isn't only about having your subject in focus: you can use depth of field as a composition technique to give your photo a particular mood.

Depth of field is the distance between the farthest and the nearest object that will appear in focus in your photo (we will later clarify what does in focus mean). You may use a shallow depth of field when you want to isolate your subject from the surrounding objects, as you can see in the following image:

Shallow Depth of Field

The yellow flower is in focus, while the background is blurred. The characteristics of the blurred part of the image is called bokeh, and mainly depends on the chosen aperture and on the physical characteristics of the lens you're using.

On the other hand, other times you may want every part of your image to be in focus, such as in a typical landscape shot.

Being able to understand how you can control the depth of field is fundamental if you want to use it proficiently and get the shots you want.

Depth of field is mainly affected by these parameters:

The focal length of your lens: the greatest the focal length, the smaller the depth of field.
The aperture you're using: the smaller the aperture, the biggest the depth of field.
The distance to the subject: the shorter the distance to the subject, the smaller the depth of field.

As we'll see later, and as you've probably experienced yourself, it's much more difficult to get a shallow depth of field than a deeper one. How many times were you striving to get a portrait with a good bokeh without success? You tried raising your aperture (reducing the f-number) but nothing, the background wasn't sufficiently blurred. Why?

We will soon discover it. These rules are fairly basic and are pretty well known to the average amateur photographer. However, these are only approximations of a more complicated formula and sometimes you may strive without success to get the results you want even if you're following all of the above mentioned advices.

Understanding the Nature of Depth of Field

Depth of field behind and in front of the object that is on focus isn't symmetric: on most conditions, depth of field will be deeper behind the subject and shallower in front of it. We won't explore the details of the depth of field equations, but it's important that you realize the following:

The ratio between the focus zone behind a subject and the focus zone in front of it tends to 1 when the distance between the camera and the subject gets shorter and is about the same order of magnitude of the lens focal length. Unless you're shooting with a macro lens, this won't be the case.
The depth of focus zone behind the subject increases as the distance from the subject increases and will reach the positive infinity at a finite distance, usually called hyperfocal distance.

What does this mean? Well, amongst other things it means that:

It's way more difficult to blur the foreground rather than the background.
If the distance from the subject is greater than the hyperfocal distance you aren't going to get that beautiful bokeh you're looking for, no matter how much you strive for it.
On the other hand, if you're looking for a picture with a really deep depth of field, just be sure your subject is farther than the hyperfocal distance.

Hyperfocal Distance

We now understand that the hyperfocal distance is responsible for at least some problems we had while getting the focus condition we looked for our shot. The hyperfocal distance H can be expressed as:

H = (f²) / (N c)

where f is the focal length, N the aperture and c the diameter of the circle of confusion. The circle of confusion, as suggested at the beginning of this post, is the criterion used to establish when a region of a photo can be considered in focus: it's the minimum diameter of the circle generated by a cone of light rays coming from a lens when a point is not in focus. Being the diameter of a physical light spot on your sensor (or on your film), this value depends on the size of the sensor: the biggest the sensor, the biggest can be c to get comparable sharpness. You can use 0.03 mm as a typical value for c.

Some properties of the hyperfocal distance are:

The biggest the focal length, the biggest H is. Please note that the relationship is quadratic: a lens with a double focal length will give an hyperfocal distance four times as big, keeping the other parameters fixed.
The biggest the aperture, the smallest the hyperfocal distance.
When focusing on an object at the distance H, the depth of field will be extend from H/2 to infinity.
When focusing on an object at a distance H or greater, the ratio between the focus zone behind the subject and the focus zone in front of the subject is infinite.

But how big is H? Here are some values for H(f, N) some common focal lengths and apertures (assuming c = 0.03 mm):

H(18mm, f/4) = 2.7 m
H(18mm, f/16) = 0.67 m
H(55mm, f/4) = 25.21 m
H(55mm, f/16) = 6.30 m
H(100mm, f/4) = 83.33 m
H(100mm, f/16) = 20.83 m
H(200mm, f/4) = 333.33 m
H(200mm, f/16) = 83.33 m

It's now apparent why focal length is often really important if you need a good bokeh. If you're shooting with a 18mm-f/4 lens, if your subject is more than 2.7 meters away there's no way to get a decent bokeh. And even if it got closer, the boken wouldn't be that good either. On the other hand, this is the reason why wide lenses are really good to get a really wide landscape in reasonable focus. Even if you were shooting with a 55mm lens at f/4, any object farther than 12.6 m (25.21 m / 2) would be in focus.

We've understood why, if you want to shoot at a subject at a given distance and you want to get a good bokeh, you must take the hyperfocal distance into account:

If your subject is nearer than the hyperfocal distance, you can shoot and tweak your depth of fields using the other parameters.
If your subject is farther than the maximum hyperfocal distance you can get with your lens, your only option is changing it.
If your subject is very close to the hyperfocal distance of the lens configuration you're using, you should consider changing the lens anyway to get a good bokeh (the reason will be explained in the next section).

Evaluating the Depth of Field

Learning your lens parameters is important and knowing the approximate hyperfocal distance of your lenses (at least for some apertures) is important if you need to quickly evaluate if the conditions in which you're going to take a shot are correct.

There's another advantage of knowing the hyperfocal distance: using a curious mathematical property of H, you can quickly evaluate the characteristics of the depth of fields at distances smaller than H without learning the complex, and not-as-easy-to-evaluate, depth of field equations. Here's how.

The nearest end and the farthest end equations of the depth of field can be expressed in terms of H and s (the distance from the subject), when s is much larger than the focal length (which is always true unless you're doing macro photography, which is not the case):

D_N = H s / (H + s)
D_F = H s / (H - s)

This equations are pretty simple, but not enough for a photographer to quickly use them when shooting without the help of a calculator! If we now consider distances s = H / n (where n is a natural integer), then these formulas simplify ever further:

D_N = H / (n + 1)
D_F = H / (n - 1)

The depth of field at a distance H/n (where n is an integer number) is the range [H/(n+1), H/(n-1)].

Much easier to calculate by mind! Also, it's apparent that for relatively small H or relatively big n you're going to have a shallow depth of field. You often won't even need to calculate the result, just remember the principle.

Using this trick, you can evaluate approximately the depth of field. For example: if you're shooting with a 200mm lens at f/4, you know that H is approximately 333 m. What's the depth of field if we're making a portrait to a subject at 10 m? 10 meters is approximately 333/30 so that, from the above formula, the depth of field will be the range [333/31, 333/29] = [10.74, 11.48]. Pretty shallow, indeed.

From this formula it's also clear why the ratio between the focus zone behind the subject and in front of it goes down from infinity to 1 when the distance from the subject goes down from H.

Conclusion

In this blog post we've introduced the concept of hyperfocal distance and explained why it is so important to understand the basic characteristics of the depth of field. Depth of field is an important tool for you as a photographer and it's omnipresent in every photography course. However, very often a photographer isn't able to evaluate the depth of fields he's going to obtain from a specific camera configuration and he's left with trial and error, without even being able to assess if the shot he's looking for is even possible to achieve.

The hyperfocal distance equation is very simple and is much simpler of many depth of fields models you can find. If you don't need to calculate it exactly, known H is sufficient in most everyday situations.

Have fun.

Adobe Photoshop Lightroom Tutorial - Part XVI - Saving And Migrating Your Adobe Lightroom Presets

2011-12-14T00:31:00.000+01:00

Part I - Index and Introduction
Part XVII - Tone Curve

As we've seen in previous posts of this tutorial, many aspects of Lightroom can be customized by users and saved into a preset. There are many kind of presets and the most commonly used are:

Develop presets.
Export presets.
External editor presets.
Import presets.
Metadata preset.
Watermarks.

Instead of repetitively applying the same configurations over and over again, you can permanently store them in a preset and load them when necessary. You can, for example, save a commonly used develop configuration (such as a color temperature setting) in a preset and apply it with just a click to a bunch of photos at a time. Or you can save metadata configuration into presets and automatically apply them during an import operation.

There are many reasons why you should know how and where Adobe Lightroom stores your presets. Some of the common scenarios where you would want to save and migrate them are:

Safeguarding your data against loss.
Sharing them across different Lightroom instances, probably because you're using more than one computer.

Imagine, for example, you create some custom adjustment brushes and save them as presets. You then migrate your catalog to resume working on another computer only to discover that your brushes are gone.

Maybe you thought that a Lightroom catalog was self contained: it is, but only to a certain degree.

Where Are Presets Stored?

Lightroom version 3 can store and use presets in two places:

In the preset folder, a unique folder per user account.
In the catalog directory (only if explicitly enabled).

By default, Lightroom only uses the user presets folder, unless you select the Store presets with catalog checkbox in the Lightroom preferences window, as shown in the following picture:

Lightroom Preferences Dialog

The user-wide presets folder is called Lightroom and its location is platform dependent. Fortunately, there's a quick way to determine which folder it is: open the Preferences dialog, navigate to the Presets tab and push the Show Lightroom Presets Folder… button (shown in the previous picture). In the case of the OS X operating system, this folder is located in ~/Library/Application Support/Adobe/Lightroom:

Lightroom Presets Folder in Mac OS X

If you decided to store the presets in your catalogs, you will find a copy of this directory into your catalog root directory.

How Can I Backup And Migrate My Presets?

This is really easy: copy them to a folder that Lightroom recognizes as a preset folder and they're will be ready to use. Just pay attention to your Lightroom configuration, as detailed in the previous section, to copy presets from and to a correct location:

If you're storing the presets with the catalog, just synchronize the catalog across computer and no more action is needed.
If you're storing the presets in the user wide presets folder, you need to back it up manually and synchronize it across computers.

An effective way to synchronize files across computer is using rsync. Using rsync you can efficiently keep in sync a folder across different machines with almost no effort and transmitting the minimum amount of data to keep in sync the target with the source. This is a specially important factor to take into account since catalogs can get in the gigabytes range very soon.

Which Approach Should I Use?

If you're using only one or few catalogs, maybe its convenient for you to change the default Lightroom behaviour and store them with your catalogs. Every time you back up your catalog, you're presets will be backed up as well. And if you synchronize a catalog to another computer, all of your presets will be available on the other machine without further effort.

However, if you're using many catalogs, you may want to store commonly used presets outside the catalogs: otherwise, you would have to create them again to any new catalog you create.

You can also use a third and completely manual approach: you can manually manage which presets you want to store and at which level. Just look for the corresponding files (the presets folder structure is pretty self-explanatory) and copy them to where you need it.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

JIRA Development Cookbook - A Book By Jobin Kuruvilla

2011-12-13T14:07:00.002+01:00

Some days ago I obtained a copy of JIRA Development Cookbook, published by Packt Publishing and available online in multiple formats, including ePUB, Kindle and PDF. I started reading it with some curiosity because it seems a serious attempt to produce a comprehensive book about JIRA development.

Here are my first impressions. I haven't finished reading it yet and I'm possibly reviewing it more deeply in the future.

Book Contents

So far, I've got a very good impression of this book. The book begins with a couple of introductory chapters about the JIRA development process and the plugin frameworks: they give you an overview of the overall development process, of the basic APIs provided to the developer and of the tools you're going to use and are required readings if you're new to JIRA development.

The following chapters are pretty self contained and each one covers a different aspect of the JIRA customization process:

Custom fields.
Issues.
Workflows.
Gadgets and reporting tools.
User interface.
Remote access to JIRA.
Various database management, customization and migration tasks.

Every chapter is a comprehensive tutorial with step by step guides, complete code examples, troubleshooting information and more in depth discussions to understand how JIRA internally works. Because of their self contained structure, you can also freely jump from chapter to chapter, according to your needs.

First Impressions

I've made several JIRA plugins and a couple of years ago, at the very first attempts, I remember digging into Atlassian documentation to find out every single bit of information I could possibly find.

I'm not the tutorial kind of guy, though: the first thing I always look for are specs. However, I recognize that it's very important to have well structured documentation, and possibly some guided tours, to significantly reduce the learning time. That's exactly what I felt it missed: Atlassian documentation is very good and the JIRA Development Hub provides examples and small tutorials for practically every aspect of JIRA you would like to customize. Unfortunately, as it often happens to wiki-style online documentation, it lacks structure to some degree.

That is exactly what this book provides: a comprehensive guide you can use to effectively kick start your JIRA customization project, be it a plugin, a JIRA service or a customized user experience.

Give Your Photos a Dreamy Haze Simulating a Diffusion Filter

2011-12-11T14:04:00.001+01:00

You've just finished tweaking a great photo of yours: you think it's great but you feel it's missing something. You think that the image conveys a feeling of peace and relax and that it would really benefit from that dreamy haze you've often seen in somebody else's portraits. But you don't know how to do it.

One of the commonly used tools to achieve to give that look and feel to an image is a diffusion filter. Dreamy wedding pictures or studio portraits (such as newborn babies') are probably done that way.
The problem is:

You need such a filter.
You need a lens which you can put that filter on.
You need to carefully plan such a shot in advance.

Fortunately, it's not difficult to simulate such an effect in post production: you only need a photo editing tool with basic filters and layer support (such as Adobe Photoshop, Adobe Photoshop Elements or The Gimp). In this blog post, we're using a technique that's particularly suitable to portrait photography. If you're trying to tweak some landscape image, however, I suggest you take a look to the blog post about the Orton effect and see which technique best suits your image.

Beware: as usual, this isn't an advice not to try and get things right out of the camera.

The Basics

To simulate the diffusion pattern provided by a diffusion filter, we're going to blur the image with a blurring filter. The blurred image itself isn't sufficient, because you're going to lose too much detail. Instead, we'll blend it with your original image to achieve the diffusion effect.

The original image we'll use in this tutorial is the following:

Original Image

I don't think this image needs an additional dreamy look and feel: in fact, this is the final post processed shot and I'm keeping it as is. However, I chose it because it's a good candidate to show you some problems you may encounter on the way.

The first thing we'll do is duplicating the background layer:

Duplicate Layer

The next thing we'll do is blurring the new layer using the Gaussian Blur filter. The rule of thumb we discussed in the blog post about the Orton effect still holds: you need to use a blur radius sufficiently wide to blur the image while preserving overall detail. In this case (the image size is 4208x3264 pixels), I'll use a 30 pixel radius to achieve the following blurred effect:

Blurred Layer - Radius: 30 px

As you can see, the image is blurred but overall detail is not lost: in the eyes, for example, you can clearly see the iris edges and most of the features of the kid's face.

Now we're ready to blend the two layers. Depending on the image, we're probably going to use one of the following blending modes:

Screen.
Overlay.
Multiply.

If you recall the discussions on the previous blog posts, these three blending modes act differently on the image:

Screen will produce a brighter image, since it brightens a pixel according to its brightness.
Multiply will produce a darker image, since it darkens a pixel according to its darkness.
Overlay will both Screen and Multiply the image, according to a pixel brightness, producing a more contrasted image and preserving highlights and shadows.

As a rule of thumb:

Assuming the exposure of the image is already correct, we're going to use the Overlay blending mode.
If your image is a bit underexposed, it may benefit from using Screen instead.
If your image is a bit overexposed, it may benefit from using Multiply instead.

As usual, you've got to try and decide yourself. In this case, since I'm happy with the image exposure, we'll use the Overlay blending mode. The result is:

Final Result - Layers Overlaid

You can clearly perceive the diffusion pattern and the dreamy haze it shed over the image.

Fine Tuning

This is just the beginning. In this case, I find the image is much too dark now. The quickest way to fix it is modifying the overlaid layer opacity. This is the result setting its opacity to 80%:

Overlaid Layer - Opacity: 80%

Beware that setting the opacity too low will also remove the dreamy haze: in this case, I usually won't go below 80% and would try to fix the image exposure by fixing the original layer instead.

Using the same technique, you can control the quantity of "blur" that you're going to add to the image.

Obviously, you could also add an additional layer below the blurred one and fix exposure on it. You could use an adjustment layer, if available, or just use the Screen blending mode to raise the image exposure. The following picture is the result of 3 blended layers (from bottom to top):

The original.
A copy of the original, using the Screen blending mode and 50% opacity.
A copy of the original, gaussian blurred, using the Overlay blending mode.

Three Layers

But The Image Is Over-Saturated

The biggest problem of the images we're producing, however, is not exposure: it's color saturation. This is a common problem when using some blending modes such as Overlay. Raising the contrast of an image, in general, will boost color saturation as a side effect. This may be good in some kinds of photography, such as landscape, but it may be bad in others, such as portrait photography. A more saturated flower may look good but... do you notice the orange hue of the kid's hue in the final images we got so far? That's something you should always try to avoid. Ultimately, this is the reason why I chose this image for this tutorial.

Fortunately, this is again very easy to fix. Assuming once more that we're happy with the initial image color saturation, I usually reduce the saturation in the blurred layer until I'm happy with it. If the photo editing tool that you're using supports adjustment layers, this is really easy: just add a saturation adjustment layer and play with it until you like the result. If your editing tool does not supports it, you're going to use the Saturation tool back and forth until you're happy with it.

However, especially in portrait photography, I usually convert the upper layer to black and white, thus removing all of the color saturation from the overlaid layer. Once more, depending on the tool you're using, you may also be able to achieve better results fine tuning the black and white conversion. Adobe Photoshop, for example, lets you adjust the RGB channels intensity during the conversion:

Abode Photoshop Elements - Black and White Conversion Window

If you're not happy with the result, you can tweak the channel intensities. Depending on the image, I'm usually pushing up or down the red channel intensity until I like the end result.

This is the final image, using a black and white blurred layer:

Final Image - Black and White Blurred Layer Overlaid

It's far more natural, even if still very contrasted.

Conclusion

We've seen how you can use very simple layer manipulations to achieve a variety of effects. So far, we've only used the Screen and Overlay blending modes, and there's a world of possibilities for you to discover.

As a rule of thumb, you've also seen as the Overlay blending mode affects your image contrast and color saturation. Although I recognize that "punchy" images may look appealing at first, I don't really like excessive color saturation in portraits and I always end up with cooler images. That's just a matter of taste, however.

Also, I find that the dreamy haze best suits less contrasted and brighter images.

Smoothing the Skin Reducing Local Contrast Using Layers

2011-12-08T17:55:00.001+01:00

In a previous post in my Lightroom series I took advantage of the Clarity tool to smooth the skin of the model. Nevertheless, the Clarity tool is not available either in Photoshop or The Gimp and many people ask how the same effect can be reproduced in these programs.

I answered this question in a previous post (Clarity Adjustment in Photoshop). The answer, however, was pretty theoretical so that in this post we will use the technique we learnt to smooth the skin in an image.

The original image, once more, is the following:

Original Image (Cropped)

The first thing we're going to do is creating a new layer duplicating the original one. Once we've done it, we use the High Pass filter to detect the transitions. The radius you need to use depends on the image (and corresponds to the amount of local contrast we're going to detect). In this image of 16 megapixels I'll use a radius of 3 pixels:

High Pass Filter - Radius: 3 pixels

We end up with a neutral grey layer where transitions are marked by lighter and darker pixels whose intensity will depend on the corresponding (underlying) pixel:

High Pass Layer

We know from our previous post that the information contained therein can be used both to raise or reduce the local contrast of our image. Since, in this case, we want to reduce it, we have to invert the layer end we end up with:

High Pass Layer - Inverted

If we now set the blending mode to this layer to Overlay the result is the following:

Resulting Image: Lowered Local Contrast

What has happened? The neutral gray pixels leave the underlying pixels unaffected. Lighter ones will screen the underlying pixels and dark ones will multiply the underlying pixels. Since pixels aren't neutral gray only at the point of transitions, we would end up with increased local contrast. However, since we've inverted the high pass layer, the local contrast is reduced.

The skin now looks smoother and you can use the high pass radius to fine tune the smoothness. However, eyes aren't sharp any more and this is something we want to avoid. Now, we have to apply this local contrast reduction only locally. How? Using a layer mask.

A layer mask is literally that: a mask, and it behaves as such. Let's imagine you take a sheet of white paper and you print your original layer over it. Now, you take another sheet of paper and you print the high pass layer over it. If you put this sheet over the other in overlay mode (assuming it would be possible), you end up with the result we just achieved. Now: you take scissors and make a couple of holes in the upper sheet just where the eyes of the model are. What would the result be? Well, the eyes from the inferior layer would be visible and wouldn't be affected by the upper layer.

Layer masks work just like that: the only difference is that you make "holes" using the black color. Layer, moreover, are more sophisticated: you can make "semi-transparent" holes using a shade of grey. Funny, isn't it?

Let's add a layer mask to our inverted high pass layer:

Layer Mask

As you can see, the layer mask is white: this means that the entire layer now contributes to the overlay effect with the lower layer. Let's now take a brush and paint over the left eye and its eyebrow. The result is:

Right Eye and Eyebrow Unmasked

As you can see, the right eye and its eyebrow have recovered all of their local contrast: pixels that we painted with black aren't affected by the upper layer any more. Let's finish painting and we end up with this result:

Final Result

You can also notice how the layer mask icon in the layers palette reflects our mask:

Resulting Mask

Conclusion

Although not available as a standalone tool, you've learnt how you can reduce the local contrast (a negative clarity, in Lightroom jargon) of a selected part of your image.

Layer mask are powerful and you can use the same technique to selectively apply any kind of effects. In this case, you could have chosen to use a blurred layer to smooth the skin, instead of going through the steps described above. Or, you could have used a bigger radius to soften the skin even more, as shown in the following picture. The only limit is your imagination.

Result with High Pass Filter, Inverted, Radius: 5 px

With the same technique, you can enhance the eyes of the model (as described in the Lightroom tutorial), applying the same adjustments in a new layer and masking out the parts of the image you want to leave unaffected.

Exposure Compensation in Post Production Using Layer Blending Modes

2011-12-08T14:55:00.001+01:00

Very often I hear people complain about what should be, apparently, a very easy thing to do: modifying the exposure of an image in post production. Truth is that if the adjustment you need is relatively small results are going to be satisfactory. Unfortunately, as long as you need to push the exposure adjustment a bit farther, results are often going to disappoint you.

Why?

Usually because of two factors:

Your image has not sufficient dynamic range to achieve the result you want (that's why you should shoot RAW if you can).
Because people don't clearly understand the physics of the human eye.

As far as it concerns the first factor, you cannot help but repeating it over and over again: you should shoot RAW if you can. Double check it. Even if you think you cannot. Some Canon point and shoots, for example, can be tweaked to shoot RAW.

As far as it concerns the second factor, here is yet another quick wrap up.

A Word of Warning: I'm a mathematician but if this is not a rigorous post. This is a quick tutorial for you to better understand some tools that are often misunderstood.

The Human Eye as a Sensor

As we stated many ways, one of the things that photographers often overlook is that the human eye is a logarithmic sensor. But what does it mean? It basically means that whenever the quantity of light doubles, whichever its frequency in the visible spectrum, you'll notice a comparable "brightness" improvement.

This also means that if you need to modify the exposure in post production, you cannot overlook this effect. You cannot just bump the channels up and down because luminance ratios must be preserved. If you don't, the dynamic range of your image will suffer and you'll end up with a flat, hazy image.

The Problem with the Brightness Tool

The problem with the Brightness tool is that, despite the name, it is not suitable to apply such a modification. It depends on the tool you're using but as far as it concerns the software most commonly used (Photoshop and The Gimp), a brightness adjustment does not what you think it does.

Roughly speaking, the brightness adjustment just adds a correction to the pixel values:

n = o + d

where o is the old value and d is the selected brightness adjustment. It might look right, doesn't it? It does shifts the histogram left or right (depending on the sign of d). But it does not preserve ratios and, as such, it is not the tool you need to tweak an image exposure preserving its dynamic range.

Here's what happens trying to fix an artificially underexposed TIFF image using just the Brightness tool (in this post I'll use The Gimp):

Original Underexposed Image

Brightness raised to 100

This test image is badly underexposed but the detrimental effect introduced by the Brightness adjustment on an image dynamic ratio won't ever be avoided.

If you like Mathematics, try to bring d to infinity and think at what happens to the (absolute value of the) ratio between two pixels value: it just goes down to 1. That's why your images will soon start to lose contrast.

Many people will then try to fix the contrast but that won't work, either.

What Can Be Done?

Preserving the ratios! To preserve the ratio, you need to correct a pixel values using a multiplier. That's what the Multiply and Screen blending modes are made for:

If you need to lower the exposure of your image, you can blend a layer with a copy of itself using the Multiply blending mode.
If you need to raise the exposure of your image, you can blend a layer with a copy of itself using the Screen blending mode.

What do these blending modes do?

Basically, they're effect is:

Screen lightens a pixel in the lower layer proportionally to the "brightness" of the corresponding pixel in the upper layer.
Multiply darkens a pixel in the lower layer proportionally to the "darkness" of the corresponding pixel in the upper layer.

What happens if you blend a layer with a copy of itself using these blending modes? It applies the very effect we were looking for!

Again, if you like Mathematics, just think about the definition of the exponential function. What happens when you're modeling a phenomenon whose variation (derivative) depends solely on its intensity? Refine this concept: is there any function whose derivative in a point x is only a function of the value of the original function in the point x? Yes: the exponential function.

We're applying an exponential transformation on a matrix of points that will be fed in a logarithmic sensor (the human eye). Just what we were looking for.

Here's what happens when we screen the test image we used before with itself (twice):

Screen Blending Mode

This is a much better result indeed.

If you're new to layers and blending modes, well, it's time you get serious about them. Here's a screenshot of The Gimp layer palette of the previous image:

The Gimp - Layer Palette

Conclusion

The Brightness and Contrast tools are often misused and it's important you understand what's going on under the hood. If you need to apply an exposure compensation, they're not the right tools. Instead, take some time to learn about layer blending modes. The Multiply and the Screen blending modes are just the beginning. Here are some additional tips:

You can mix and match them to achieve more sophisticated results and you can fine tune the effect tweaking the layer transparency.
If screening or multiplying two layers is too much compensation for your image, just make the layer a bit more transparent.
If you're looking for a way to raise the overall contrast of an image, try to screen and multiply it.
You may also want to take a look to the Overlay blending mode, which is a mix between the Screen and the Multiply (it screens dark colors and multiplies bright ones).

Adobe Photoshop Lightroom Tutorial - Part XIV - Using Presence Controls to Smooth the Skin

2011-12-08T12:54:00.001+01:00

Part I - Index and Introduction
Part XV - Speeding Up Your Workflow Using Presets and the Painter Tool

Local Contrast to Make Softer or Rougher Surfaces

In a couple of previous posts (see here and here) we learned about local contrast and how this effect can be easily achieved in Adobe Photoshop Lightroom. Local contrast, or Clarity in Lightroom's jargon, literally refers to the amount of contrast that's present locally in areas of colors and tones transitions of your image. Local contrast allows you to tweak your image without modifying the overall contrast and the tonal scale of your image:

Increasing the local contrast "sharpens" transitions and gives rougher surfaces.
Decreasing the local contrast gives smoother surfaces.

Although clarity can be adjusted at the image level (I often raise it a bit to get punchier images) by its own nature local contrast is an adjustment that you often want to brush into your image.

Smoothing the Skin

One of the uses of a negative clarity is skin smoothing. Skin isn't so smooth a surface and unless your model has got a perfect one and your lighting conditions are optimal, his skin won't appear as smooth as we'd like. Here, we're not talking about skin imperfections (you're going to manually remove those with other brushes) but skin texture.

Depending on the image you'd like to get, you may need to correct the skin texture somehow. If you want to give your portrait a "dreamy" and "diffused" look and feel, this is a way to achieve it. As usual, there are plenty of way of doing it in Photoshop but this post will focus on the clarity (local contrast) adjustment. One of the good things of this adjustment is that it's really easy to use and it usually gives very good results with little effort.

To have an idea of what you're going to achieve, you can lower overall clarity of a portrait and see what happens. The reduced local contrast is going to take away sharpness to your model skin and smooth its surface. But unless you're happy with this result, you'd better take a brush and apply clarity locally.

Adobe Photoshop Lightroom ships with a Soften Skin brush since version 3. This brush is defined as follows:

Adobe Photoshop Lightroom - Soften Skin Brush

As you can see, this brush applies a negative Clarity adjustment of -100 (the minimum) and raises the Sharpness a bit to balance the extreme smoothing effect. There's no silver bullet here: you've got to try and tweak the brush parameters yourself until you get the result you expect.

Personally, I don't like this brush: it's too "extreme". I'd rather use a Clarity adjustment in the [-50,-60] range and adjust sharpness and saturation according to my taste.

A personal suggestion: in portraits where you're looking for a really smooth skin, try to desaturate the skin a bit. I find the results are more natural.

A Test Image

This is a crop from an image in which I want to brush in some negative clarity to smooth the skin of the model. This image was taken with bounce flash in a small room: the flash was bounced with an angle close to 80 degrees and the light hasn't lit evenly the face of the model. Remember: photography is all about light and you should try to get the results you want right out of the camera. Unfortunately, sometimes we cannot prepare the setup we need to get the right shot and that's when it's right to fix things in post production.

Original Image (Cropped)

Look at the original image. This is a cropped section of a shot a took by surprise: the model wasn't even wearing any make up. Besides having to remove some skin imperfections, I really don't like the overall texture of the skin. Also, the bounce flash hasn't properly lit the eyes and the skin underneath them. That's what I'm trying to fix with a negative clarity adjustment: I'll try to reduce the local contrast without affecting too much the overall texture of the skin or completely removing those shadows ending up with an unnaturally flat image.

Final Image (Cropped)

This is the result after brushing in some negative clarity (-70) and some sharpness. The result is much smoother but it's not yet unnatural. Since it's not a studio image and I want to preserve the overall look of the shot, I don't want to go any further.

In this image I also tweaked the eyes as explained in the previous post.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

Adobe Photoshop Lightroom Tutorial - Part XIII - Using Presence Controls To Enhance The Eyes

2011-12-08T11:49:00.001+01:00

Part I - Index and Introduction
Part XIV - Using Presence Controls to Smooth the Skin

In the previous parts of this Adobe Photoshop Lightroom Tutorial we've described how presence controls work in order for you to have a deeper understanding of what's going on during the development of your image.In this part of the tutorial we'll use some of these controls to slightly "enhance" the eyes of a model and make them "pop".

The Original Image

The original image was taken with a bounced flash: we decide to bounce the flash from the ceiling to achieve a softer and more diffused lightning but, sometimes, parts of your subject won't be sufficiently lightened. It's not generally a problem, since soft shadows are part of the effect we want to achieve with bounced flash, but sometimes we want eyes to be brighter. Because of their natural position and depending upon the lightning conditions (we usually avoid light to bounce directly on them), eyes are often poorly lit with a resulting loss of color saturation and natural look.

Original Image - Poorly Lit Eyes

In this example photo the effect is subtle: as an absolute value, you can consider eyes to be properly exposed. However, this is an effect of the slight overexposure I gave to the entire shot. If you have a look at the skin tone of the model, you'll realize that the key of this image if fairly high.

Tweaking the Iris

Adobe Photoshop Lightroom version 3 already comes with a brush that's suitable to enhance the iris. You can choose a Lightroom brush, or even create one of your own, selecting the brush icon just below the histogram (in the Develop module), and then choosing a brush from the drop-down menu.

Lightroom Irish Enhance Brush

Let's have a look at how this brush is defined and try to understand what's going on. Take into account that every image is different and that there's no silver bullet:

It raises the exposure of about 2/3 of an f-stop.
It raises the saturation.
It raises the local contrast (clarity).

Pretty intuitive, isn't it? The exposure compensation will make the iris brighter and the increased saturation will make its color pop. The local contrast enhancement is a subtler effect that might not be very visible depending on the iris. Remember from a previous post that local contrast is a technique used to add depth to an image raising the contrast only locally, without affecting the overall dynamic range. Depending on the dynamic range found in the iris, this adjustment will have a bigger or smaller effect. You'll probably notice it more in clear irises, such as blue eyes ones, where you often find radial "stripes" of different tones: clarity is going to make them really pop.

Tweaking the Sclera (the White of the Eye)

The sclera (the white of the eye) may be affected by the same problem: a slight underexposure. Other times it may be affected by problems that are even worse and it may appear not at all white. To quickly fix such a problem we can use a different brush with the following settings:

Custom Brush - Tweaking the White of the Eyes

What does this brush do? The following:

It raises the brightness.
It decreases the saturation.

As we recall from the previous post, raising the brightness is a way to brighten an image without affecting its white point. That's why this is one of the (few) cases in which I prefer to use brightness instead of exposure: the sclera, as well as teeth, may be already bright in your image. Raising the exposure of such a zone may clip some channels: for this reason, we choose to be conservative and raise the brightness instead. Decreasing the saturation is going to remove any color cast that your eyes may have, such as small rashes.

The Final Image

Here you can see the final image. You can notice how the irises are deeper and more saturated and the sclera, especially the one of the model's right eye, is brighter. The glance has more depth. The effect is subtle and it had better be: eyes are going to attract people's attention and you don't want to give them an unnatural look.

Final Image (Cropped)

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

A New Firmware Is Available for the Nikon D5100

2011-11-27T16:49:00.001+01:00

Nikon has released an updated firmware for its consumer DSLR camera, the Nikon D5100. The new firmware, v. 1.01, officially solves the following bugs:

Some memory cards weren't recognized correctly.
The selective color retouch tool sometimes left the border of an image unchanged when the image quality was set to NEF+JPG and the image size was set to M or S.
The exposure differential when taking HDR images using matrix metering and automatic exposure differential is not fixed to 2 EV any longer.

Installing the firmware is straightforward:

Copy the firmware image to a memory card root folder and insert the card into the camera.
Choose the Firmware version item in the camera Configuration menu.
Use the Update menu item and follow the on-screen instructions. The upgrade will take less than a couple of minutes.
Turn off the camera and remove the memory card.
Turn on the camera, check if the new firmware has been installed, using the Firmware version item in the camera Configuration menu.
Turn off the camera and wait at least 5 seconds before using it.

Undocumented Changes

I discovered that the weird Auto ISO behaviour with a hot-shoe mounted flash that I described in another post has suffered a change. With the new firmware, the Auto ISO behaviour with both the pop-up flash and a hot-shoe mounted flash is the same and is consistent with the Auto ISO documented behaviour: the ISO is automatically raised up to the maximum value specified in the camera settings.

Network Configuration in Solaris 11 with NWAM Profiles

2011-11-13T12:23:00.001+01:00

Oracle has just released the Solaris 11 operating system, the new production ready Solaris major release. It's an "interesting" release since it's the first Solaris major release under the Oracle egemony and it inherits all of the technologies many of us have been using, in the last few years, in the Solaris Express and OpenSolaris releases that Sun Microsystems used to provide.

This blog post is the first part of a series of quick wrap ups for the impatient to quickly start and configure their new Solaris 11 servers. My advice is always the same: read the manual.

Network Configuration Changes in Solaris 11

Network configuration in Solaris 11 is pretty different than it was in earlier Solaris releases (including Solaris Express) and many administrators may be taken by surprise. Some of these changes were introduced in the corresponding OpenSolaris projects, such as Crossbows, and may be known by many of us. To sum things up, the major differences are the following:

Network configuration is now managed by a profile.
The dladm command now centralizes the configuration of layer 2 datalinks: many tasks performed by the ifconfig command on previous Solaris releases are now to be performed using the dladm command.
Datalink names aren't bound to their hardware driver name any longer.
IP interfaces on layer 3 are configured by using the ipadm command: the venerable ifconfig command has been deprecated in the Solaris 11 release.
IP network multi pathing (IPMP) groups are now implemented as IP interface and as such, configured with the ipadm command.
The new ipmpstat command has been introduced to gather statistics about IPMP groups.
Network virtualization has been implemented on the network device level.

The Solaris 11 Network Stack

The new Solaris 11 network stack is similar to Solaris 10's. Yet, some improvements have been introduced that administrators are simply going to love.
In the new network stack, the software layer has been decoupled from the hardware layer: this means that:

The network configuration of a system (or a zone) is insulated from the hardware it's running upon.
As already stated, datalink names can be customized.
Many network abstractions (such as VNICs) are managed in the datalink layer: this means that all of the datalink configurations can be centrally managed with one administrative interface.

On Solaris 11, then, datalinks aren't named from the underlying physical devices and, by default, are named using the netn scheme, where n is a 0-based integer index. This apparently minor modification has a very important consequence: if you modify the underlying hardware, a network configuration may still be valid if the datalink name is left unchanged. This is really handy, for example:

If the underlying hardware of a box changes.
If you migrate zones across systems.
If you write generic configurations for a wide set of boxes.

The mapping between a datalink and the underlying physical device can be inspected with the dladm command:

$ dladm show-phys

LINK MEDIA STATE SPEED DUPLEX DEVICE

net0 Ethernet up 1000 full e1000g0

net1 Ethernet up 1000 full e1000g1

Network Auto-Magic (NWAM)

Long time users of older Solaris Express releases will remember the introduction of the Network Auto-Magic feature into the operating system. NWAM is a feature that automates the basic network configuration of a Solaris box. NWAM in Solaris 11 has been greatly enhanced and it now supports the following concepts:

NCP.
Location.

An NCP is a an administrative unit that specifies the configuration of the components of the network setup such as physical links and IP interfaces. An NCP is itself made up of NCUs (Network Configuration Units) representing the configuration of a physical link or interface.

A Location profile is another administrative unit that let the administrator specify:

The conditions under which a profile should be activated.
The naming service configuration.
The domain name.
The IP filter rules.
The IPSec policy.

At a given time, only one NCP and one Location profile will be active in a Solaris system.

NWAM is handy when a system network configuration is changed often and an administrator, in those cases, can encapsulate the different and required configurations in profiles (NCPs and Location profiles) and activate them when needed.

If you're using the Solaris 11 desktop, you can use the Network Preferences application (which can be found into the System/Administration menu) to quickly build NCPs and Location profiles.

Network Preferences

In the following sections we will use some NWAM administrative commands but we won't dig into this subject any more and let NWAM administration be the topic of another post.

Configuring the Network

Depending on how a newly Solaris 11 installation has been performed, your initial network configuration may differ. If you've installed it from the Live CD, the Automatic NCP and the Automatic Location profile are active. These profiles are pretty simple: they configure every IP interface and the name service using DHCP, leaving any other configuration option (IP filters, IPSec, etc.) disabled.

If you're using Solaris on your PC this configuration may be good for you but chances are you might be installing some server that requires a less trivial network configuration.

Creating an NCP profile

The first thing you're going to do is creating a new NCP:

$ netcfg create ncp datacenter

The datacenter NCP will be the container of our configuration and we will add the NCU that we need for every link and IP interface we're going to configure.

# netcfg
netcfg> select ncp datacenter
netcfg:ncp:datacenter> create ncu phys net0
Created ncu 'net0'. Walking properties ...
activation-mode (manual) [manual|prioritized]>
link-mac-addr>
link-autopush>
link-mtu>
netcfg:ncp:datacenter:ncu:net0> end
Committed changes
netcfg:ncp:datacenter> create ncu ip net0
Created ncu 'net0'. Walking properties ...
ip-version (ipv4,ipv6) [ipv4|ipv6]> ipv4
ipv4-addrsrc (dhcp) [dhcp|static]> static
ipv4-addr> 192.168.1.53
ipv4-default-route> 192.168.1.1
netcfg:ncp:datacenter:ncu:net0> end
Committed changes
netcfg:ncp:datacenter> exit

With the netcfg command we created an NCP with the following characteristics:

It has an NCU for a physical interface (net0). This NCU has been configured with default values for all of its properties (such as MAC address or MTU).
It has an NCU for an IP interface (net0). This NCU has been configured with a static IPv4 address and a default router.

If you activate this profile, your system will reconfigure the network according to the settings of this NCP:

# netadm enable -p ncp datacenter

Enabling ncp 'datacenter'

If we now check the IP interfaces we can see how they've been configured according to the above-mentioned NCUs: the net1 IP interface is up while the net0 interface has disappeared.

# ipadm show-if

IFNAME CLASS STATE ACTIVE OVER

lo0 loopback ok yes --

net1 ip ok yes --

If we check the IP addresses currently used, the ipadm command confirms that only net1 has been assigned an address which is the static address we configured in the NCU. Again, net0 has disappeared.

# ipadm show-addr

ADDROBJ TYPE STATE ADDR

lo0/v4 static ok 127.0.0.1/8

net1/_a static ok 192.168.1.53/24

lo0/v6 static ok ::1/128

If we know check the state of the datalinks, we can see that net0 is in the unknown state while net1 is up.

# dladm show-phys

LINK MEDIA STATE SPEED DUPLEX DEVICE

net0 Ethernet unknown 1000 full e1000g0

net1 Ethernet up 1000 full e1000g1

If we wanted to add both the net0 datalink and IP interface into the profile, we could simply modify it and create the corresponding NCUs.

If we now try to resolve some name, however, we discover that it's not going to work. If you remember, we're still using the Automatic location profile which configure the name resolver using DHCP. In this case, however, DHCP isn't being used so that the resolver is not going to resolve any name.

What we need now, is a corresponding location profile.

Creating a Location Profile

To configure the resolver settings, we can now create a new location profile, using once more the netcfg command:

netcfg> create loc datacenter
Created loc 'datacenter'. Walking properties ...
activation-mode (manual) [manual|conditional-any|conditional-all]>
nameservices (dns) [dns|files|nis|ldap]>
nameservices-config-file ("/etc/nsswitch.dns")>
dns-nameservice-configsrc (dhcp) [manual|dhcp]> manual
dns-nameservice-domain>
dns-nameservice-servers> 192.168.1.1
dns-nameservice-search> yourdomain.com
dns-nameservice-sortlist>
dns-nameservice-options>
nfsv4-domain>
ipfilter-config-file>
ipfilter-v6-config-file>
ipnat-config-file>
ippool-config-file>
ike-config-file>
ipsecpolicy-config-file>
netcfg:loc:datacenter>
netcfg:loc:datacenter> end
Committed changes
netcfg> end

As soon as we enable the newly created location profile, the resolver is going to use the configured settings and it's just going to work:

$ netadm enable -p loc datacenter

Enabling loc 'datacenter'

$ nslookup www.oracle.com

Server: 192.168.1.1

Address: 192.168.1.1#53

Non-authoritative answer:

www.oracle.com canonical name = www.oracle.com.edgekey.net.

www.oracle.com.edgekey.net canonical name = e4606.b.akamaiedge.net.

Name: e4606.b.akamaiedge.net

Address: 2.20.190.174

Conclusion

As you can see, configuring the basic network settings in a Solaris 11 system is clean and easy. The new administrative interface lets you easily define, store and activate on-demand multiple network configuration for your system without the need of writing and maintaing multiple copies of the old style Solaris network configuration files.

Orton Imagery in Adobe Photoshop

2011-11-11T10:04:00.001+01:00

The Orton imagery (a.k.a. Orton effect), named after the photographer Michael Orton, is a technique whose goal is achieving regions of high details and regions of low details in the same image.
The original technique was developed making sandwiches of slide films of the same scene taken with different levels of overexposures and different focussed areas. However, one could also choose to blend completely different slides to achieve more dramatic and artistic effects.

The Orton effect can be easily replicated in the domain of digital photography and, depending on the shooting conditions, even without bracketing exposures or voluntarily defocusing some shots. If you're shooting RAW, it's really easy to modify the exposure of a shot without loosing information, at least for relatively small adjustments: it all depends on the specific camera and RAW file format.

I agree that it's always better if you try to get things right on camera, but sometimes you simply don't known the effects you're going to use in post production. However, since what we need is usually just a maximum +2 f-stop overexposure, there's really no issue doing it during your post-production workflow.

The Basics

As we stated in the introduction, the Orton effect originated with slide films:

Two shots differently overexposed were taken.
One of them was taken out of focus.
The two positive slides were "sandwiched" one above the other.

Since one of the two shots has to be taken out of focus, perfect alignment isn't an issue so don't worry if you're not shooting with a tripod when you realize you're going to take an Orton-candidate shot.

In the digital domain, you aren't going to physically slide any slide and you're going to blend a couple of layers instead. To simulate the effect of two positive layers one above the others, we're going to use the Multiply blending mode:

Multiply darkens the lower layer based on the darkness of the upper layer.

This is consistent with what happens to a slide sandwich:

Being positive, the white is transparent, and the superposition of two transparent slides filters no light (if we ignore the effect of the slide plastic material itself).
Any non transparent area will filter (darken) the light that passes through hence two overlapped slides will filter the light twice.

Overexposing the Image

Since the overlapping layers will be multiplied, they should be overexposed so as to preserve the desired exposure of the resulting image. There's no formula to determine how much the two layers must be overexposed, just trial and error and a bit of experience.

As a rule of thumb, a total overexposure of 2 or 3 f-stops will usually give good results. However, care must be taken:

To avoid to clip some channel up: this may be an issue with images with large highlight areas that will be clipped with little overexposure.
To avoid to clip some channel down: this may be an issue with images with large shadow areas that are going to clip the black point when multiplied.

Usually, my golden rule is:

The darker an image, the more I overexpose it, paying attention not to clip the white.

Once a channel is clipped, information is lost. Even if you multiply two layers where the white is clipped, the result in the clipped pixels will still be white.

Defocusing the Image

This is the most critical step, indeed. If you defocus the image on camera, you're taking advantage of your lens bokeh. This is something difficult to replicate in post production, and few software have some better blurring algorithms rather than motion blur or gaussian blur.

I usually rely on the gaussian blur filter to defocus an image in post production but, if you're a Photoshop user, you could use the more advanced lens blur filter.

How To Overexpose

As I said, you've got two choices:

Either you overexpose on camera.
Or you overexpose on post production.

If you're choosing the quickest path, I seriously recommend you do it only if you shoot RAW. Shooting RAW has got the advantage of recording more dynamic range than what it's actually shown in the picture. When you overexpose a RAW image you're going to get better results, especially in the shadows area, where the additional information will bring up more details in the darkest tones.

For the sake of this example, we're going to overexpose a RAW image in post production using Adobe Lightroom. As you can see from the histogram, the blue and red channels are going to be clipped as soon as we overexpose the image.

Histogram of the Original Image

In this case, I decided to apply a minimum overexposure of 1 f-stop and postpone the final decision after checking the final result. The original image and the resulting overexposed image by 1 f-stop are the following:

Original Image

Image Overexposed by 1 f-stop

Much of the area of the petals may seem burned out but, fortunately, there's still sufficient information for the multiply blending mode to bring down in the final result, as you can see from the following image:

Orton Effect in Photoshop

Now that the two overexposed images are ready, let's switch to Photoshop to compose the final Orton image. This process is pretty simple and Photoshop is not required: you can use Photoshop Elements or The Gimp, just to cite a few. In this case, we're going to use Photoshop Elements.

The first step is trivial: opening the two images.

The Two Images Opened in Photoshop Elements

The second step is pasting the second photo as a new layer in the first photo. The quickest way to do it is:

Use the Select/All menu option.
Choose the Move tool from the palette (or press the V key).
Drag the selected image into the other. In Photoshop Elements you are required to drag it over the title tab, first, to have Photoshop switch between the two documents.
Photoshop will automatically create the second layer for you.
Use the move tool to align the two images.

In the layer palette, you should see the newly created layer.

Layer Palette - Resulting Layers

Now, change the blending mode of the upper layer to Multiply.

Layer Palette - Second Layer Blended with Multiply

The result so far should be a darker, more contrasted and more saturated image such as the following:

Resulting Image After Applying the Multiply Blending Mode

The last step is blurring the upper image. In this case we're going to use the gaussian blur filter but, if you've got some other blurring filter, you can try and explore new possibilities.

Also, the "quantity of blur" (radius, in the case of the gaussian blur filter) will depend on your image. For a good Orton effect you need to blur an image so that details are lost but shapes preserved. With a flower of such size in a 16 Megapixels image, I applied the gaussian blur filter with a radius of 20 pixels to achieve the following result (only the blurred layer is shown):

Gaussian Blur Filtered Layer with Radius = 20 px

The Result

The final result is this:

Final Result - Orton Effect

As you can see, the Orton effect is faithfully reproduced.

It's important to realize that every image is different, and so is the effect that you've got in your mind. The parameters you're going to use can be tweaked in order to achieve the desired effect:

If you want a softer (or sharper) image, just raise (or lower) the gaussian blur radius.
If the image is too dark, raise the overexposure of one or both of the layers.
If the image is too light, lower the overexposure of one or both of the layers.

A Tip For Who's Not Shooting RAW

If you want to apply this effect to a non-RAW image, you need to overexpose it using other means. The only thing you can refrain from trying is using the Brightness adjustment. It's just not designed for that and the results you're going to achieve will be awful, at best.

A good technique to simulate an overexposure in Photoshop (or The Gimp) is using the Screen blending mode. The screen blending mode can be thought as the opposite of the Multiply blending mode:

It brightens the lower layer proportionally to the brightness of the upper layer.

Blending an image with itself with the Screen blending mode is a good way to simulate an overexposure.

The Grey Blog Has Switched to Dynamic Views

2011-11-07T21:22:00.000+01:00

After some weeks of testing, I've finally decided to switch to Dynamic Views. Dynamic Views, in case you don't know, are a new set of Blogger templates. They aren't just templates, however, since they introduce a major change in both the authoring experience of us, the Blogger authors, and of you, the readers. Here's an introductory article about Dynamic Views from the Official Google Blog.

I've chosen the Magazine theme as the default Dynamic Views theme for this blog, but you can change it and choose any of the available ones using the toolbar:

Changing the template was a difficult decision for me. First of all, I'm not a web guy. Absolutely. I just picked a template I liked, used it and customized it a little bit over time. When I first saw Dynamic Views, they really surprised me. They were "clean" and much easier to read than the average Blogger template. Above all, I realized they were going to need very few, if not any, modifications: I just had to pick one and apply it.

You, the reader, can enjoy a new and very readable interface with infinite scrolling. And if you don't like the Magazine theme, just change it. I, the author, am not going to fiddle with the template any longer.

Except for one "glitch": HTML headers, especially <h4/>, <h5/> and <h6/> headers, historically used to mark the titles of a blog post, aren't styled in the default templates, with great detriment of the readability of the old posts. I was forced to add attach new CSS to the template to have, at least, <h4/>, <h5/> and <h6/> headers printed in bold face. Unfortunately, I used both <h2/> and <h3/> headers in older posts and they will show up incorrectly: Blogger styles those headers in its own templates, and I'm not going to fix that in my custom CSS (hey, I told you I'm not a web guy).

I hope like it!

Clarity Adjustment (Local Contrast) in Adobe Photoshop

2011-11-07T00:15:00.003+01:00

In a post of my Lightroom tutorial series, we've seen how the Clarity tool lets you apply both positive and negative local contrast adjustments. The Clarity tool comes from Adobe Camera RAW, used by Lightroom under the hood, and it provides a really quick and easy way to perform a task that, otherwise, would require much more time to achieve.

Adobe Photoshop, for example, does not provide such a simple way to modify a picture local contrast and by its own nature, this kind of adjustment cannot be achieved with tools that modify the overall image, no matter how complex they are: you are not going to raise only the local contrast using the Contrast, the Levels or the Curves adjustment.

Even if you're a Lightroom user, there are times when you're going to use Photoshop (or similar programs) in your workflow: I deem necessary to know how you can achieve the same result when you cannot rely either on Camera RAW or Lightroom. The good news is that you can achieve the result both in Photoshop and in Photoshop Elements, the stripped down version of Photoshop aimed at beginners and amateurs.

The Unsharp Mask

The Unsharp mask is a tool that's best known to Photoshop users to sharpen an image. It's funny how names can be so misleading at times, isn't it? If you're interested about the history of the technique this name comes from, you can have a look at the Wikipedia article about it.

However, as far as we're concerned, the important thing is the following: the unsharp mask can be used to raise the local contrast of an image in a very simple way.

You can see the Unsharp mask window in Photoshop Express in the following picture:

Photoshop Elements - Unshard Mask Window

Unsharp mask adjustments are applied according on three parameters:

Amount.
Radius.
Threshold.

Usually, when you use the Unsharp mask tool to sharpen an image you select a relatively small radius and a large amount. On the other hand, if you use a relatively large radius and a small amount, the effect will be a local contrast enhancement. If you read the Wikipedia article about this technique, the radius is used to tell how much the image should be blurred during the process of detecting transitions.

In the following example, you can see the effect on the same image we used as an example of the Clarity adjustment in the aforementioned post:

Original Image

Unsharp Mask - Amount 20%, Radius 50, Threshold 0

What About Negative Clarity (a.k.a., Reducing Local Contrast)?

The Unsharp mask is an easy way to enhance the local contrast of an image: so far so good. But if you've used the Lightroom Clarity tool, you're probably missing negative clarity adjustments as well! There's no way to reduce the local contrast using the technique seen so far and you must rely on other tools.

To understand how you can achieve negative clarity, we will first look at how positive clarity can be achieved manually (reproducing the steps that are performed by the Unsharp mask tool).

The first steps is detecting transitions. In film photography, the process was pretty complex. Photoshop makes it easy: that's what the High pass filter is meant for. If we use a radius of 1.5 pixels, this is the result:

High Pass Filter - Radius 1.5 pixels

The result is:

Neutral grey pixels where no transitions were detected.
Colored pixels where transitions were detected.

This new layer will be superimposed to the original using the Overlay blending mode. The neutral grey pixels won't affect the underlaying pixels while pixels marking transactions will enhance the local contrast. This happens because the Overlay blending mode multiplies (darkens) dark areas and screens (lightens) light ones. The final result is the following:

High Pass Filtered Layer Overlaid on the Original Image

There's no doubt that using the Unsharp mask tool is much quicker when we need to enhance local contrast. What about negative clarity, then? Simply invert the layer generated by the high pass filter:

High Pass Filtered Layer Inverted and Overlaid on the Original Image

Pretty much the same effect you'd get in Lightroom using negative clarity, only a bit more difficult.

Adobe Photoshop Lightroom Tutorial - Part XII - Presence Controls

2011-11-06T19:01:00.002+01:00

Part I - Index and Introduction
Part XIII - Using Presence Controls To Enhance The Eyes

Presence Controls

Last but not least, the Basic panel offers a group of control labelled Presence and made up of:

Clarity.
Vibrance.
Saturation.

For the sake of simplicity, let's start from the last one: saturation.

Saturation

To make a long story short, saturation controls the intensity of a color. The Saturation slider in Lightroom lets you uniformly modify the saturation of the colors in an image in a [-100, 100] range:

A -100 saturation adjustment corresponds to no saturation at all and the result will be a monochrome image.
A 100 saturation adjustment corresponds to doubling the saturation of the colors.

Beware that when you increase the saturation of an image, colors channels may be clipped and as a result color shifting may occur.

I don't use the saturation tool very often, partly because I'm not so fond of too "punchy" images, and partly because of its own non-selective nature: more often than not, I only need a more selective kind of saturation enhancement:

I need to boost the saturation of a selected set of colors.
I don't want skin tones to saturate and have that orange cast.

Truth be told: I almost only use the saturation slider to completely remove the saturation of an image to produce a monochrome one. Why not simply tell Lightroom to convert the image to black and white, then? Well, just because Lightroom, by default, uses a black and white color mix that's not uniform across the spectrum (as we'll see in a future post). Sometimes it's a good starting point, sometimes it's not. Only trying with a specific image can tell.

Lightroom, as we're going to see in the following seections, provides good solutions to many of the aforementioned problems, and that's the reason why I don't use the saturation adjustment so much.

Vibrance

The Vibrance adjustment is a selective and non uniform saturation adjustment with the following characteristics:

It tries to avoid channel clipping.
When raising the saturation, it has more effect on lesser saturated colors than on more saturated ones.
It tries to preserve skin tones.

As a quick example, have a look at the following series of image:

Original Image

Saturation -75

Saturation +75

You can see as Saturation raises and lowers uniformly the saturation of the colors in the image.

However, this is the effect of the same adjustment using the Vibrance tool:

Vibrance -75

Vibrance +75

The Vibrance tool reduces and raises the saturation of the least saturated colors, in this case the background greens, leaving the more saturated colors, in this case the yellow petals and its orange shades toward the center, almost unmodified. In this specific case, you could also use Lightroom to selectively raise the saturation of the green channel (as we'll see in a future post).

However, the Vibrance tools is a handy tool that can help you apply saturation adjustment in a really quick way, especially in portrait photography when things can get really tricky when trying to preserve the skin tones of our models. Had we applied such a saturation adjustment in a portrait, orange shades would probably had popped up in our subject's skin pretty much as they popped up in the petals of this flower. In those cases, only Photoshop would be your friend: you'd use layers and layer masks to preserve the tones in selected image regions. Fortunately, Lightroom gets in the way and provides this quick solution to such a common problem.

Clarity (And Local Contrast)

The Clarity adjustment lets you add depth to an image by modifying local contrast. But what's local contrast, first of all? Here's a really quick introduction about this problem.

The physiology of the human eye is such that, in certain circumstances, a photo cannot be a faithful representation of what we perceive. This is especially true when dynamic range is taken into account. You have surely noticed how a well your eyes can see a scene with a high dynamic range (such as a landscape with both strong lights and deep shadows) and how bad the same scene look when you shoot it, no matter the effort you put into it. When we move our eyes around, they'll quickly adapt to the light conditions of the part of the scene we're focusing on, although you may have the impression of perceiving the entire scene as if no adaptation has occurred. On the other hand, when you take a shot you have to choose an exposure, and if the dynamic range of the scene you're taking is too high, you will simply miss the shot: either you burn the highlight or you lose details in the shadows. If you've heard about HDR (High Dynamic Range) imaging, you'll probably realize what the central idea of that technique is: you take multiple shots of the same imaging bracketing the exposure and blend them together in a single image, preserving the intensities you need across the dynamic range of the picture. This way, you artificially build a visual representation of what our eyes perceive when they move, and compensate, across regions of the image with big luminance differences.

You may think of local contrast as a technique to achieve the opposite goal: you selectively raise the contrast of light-shadow transitions to give more dynamic range to your image. However, instead of raising the overall contrast of the image (where both white and black points are moved and clippings may occur), the adjustment in only performed in smaller regions of the picture, leaving the overall black-white difference unmodified.

Lightroom lets you adjust the local contrast by both positive and negative values, in the [-100, 100] range. Let's see some examples of how Clarity works.

Original

In this picture, the majority of pixels find themselves on the opposite sides of the range: the background is nearly black and the flower is white. Neither white nor blacks are clipped. Since the maximum luminance difference in the flower's pixels is less than 1 f-stop away, you may want to apply some adjustment to give the flower some more depth. Raising the overall contrast, as we've seen in a previous part, will only make things worse:

Contrast +100

Raising the overall contrast is going to raise the differences between black and white, but doing so means compressing whites even further, and the result will be a flower even flatter than before. You may be tempted to apply the opposite adjustment and bring overall contrast down:

Contrast -50

In fact, reducing the overall contrast expands the histogram in the recovery and in the rightest part of the exposure zone pushing them towards the center of the histogram. The flower will indeed gain depth. Unfortunately, the overall contrast reduction is going to expand the blacks and the shadows as well, pushing them towards the center of the histogram. The final result is not probably what we were looking for since the image is now flatter and duller.

Once again, there's no need to leave Lightroom and open Photoshop. The Clarity adjustment is just what we were looking for:

Clarity +50

Increasing the local contrast has raised the depth of both the flower and the leaves, leaving the overall contrast unmodified. The white and the black points do not move and we introduce no clipping at all.

Clarity adjustments are often subtle, and I suggest you zoom out when you apply it. Nevertheless, it's a very handy adjustment which many pictures can benefit from. Look at the following example (to appreciate the difference you may need to open the liked image):

Original Image

Clarity +60

Original Image

Clarity +75

Negative Clarity

The Clarity tool lets you apply negative clarity adjustment. Why would you want to reduce the local contrast of an image? Reducing local contrast has a softening effect that may be result pleasing in some kind of photos. Some portraits and some nature images, for instance, may benefit from a slight reduction of clarity, if you want to achieve a "dreamy" or "soft" mood without spending much time on applying more complex effects such as the Orton effect. In the following example you can see how a negative clarity affects the image of the two purple flowers that we've previously seen:

Clarity -50

Local Contrast in Photoshop

The Lightroom Clarity tool is a very handy tool: you can brush a negative clarity adjustment on the skin of your model, for example, as a quick and effective way to smooth his skin. I often hear people ask how can local contrast be adjusted in Photoshop. It's not as straightforward as in Lightroom but I described an easy way to achieve the same effect in another post.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

Adobe Photoshop Lightroom Tutorial - Part XI - The Tonal Scale

2011-10-30T21:27:00.003+01:00

Part I - Index and Introduction
Part XII - Presence Controls

Adjusting the Tonal Scale

The Basic panel of the Develop module contains the editing tools to control the tonal scale of the image. Finer tonal scale adjustments can be performed in a variety of ways:

Using the basic tonal scale sliders.
Using the Tonal Curve tool.
Using the histogram.

The effect of using the tonal scale sliders in the Basic panel and the histogram is equivalent: in fact, the histogram just provides an easier (and more "visual" way) of adjusting the tonal sliders. The Tonal Curve tool (or an external program as well) provide a more flexible and powerful way to adjust the tonal scale, but my advice is: always start editing your images fixing the tonal scale using the tonal scale sliders. Only then, perform additional corrections using more advanced tools.

Lightroom provides the following tonal scale sliders:

Exposure.
Recovery.
Fill light.
Blacks.
Brightness.
Contrast.

The first four sliders let you adjust the tonal scale of the image with specific emphasis on a specific region of the histogram. Lightroom visually divides the histogram zones into the regions shown in the following images:

If you want to adjust tones in a specific region, you can click and drag the region to be modified in the histogram: depending on the direction you drag the histogram to, the tonal scale will be adjusted accordingly. Each region corresponds to one of the tonal scale sliders and the corresponding adjustment will mainly target a specific zone, although the entire histogram will be modified as a result (shifting it, expanding it or compressing it).

In the following sections we will describe each tonal scale adjustment.

Exposure

The Exposure adjustment is usually the first adjustment you will use since it fixes the overall exposure of an image, with particular emphasis on the high values of the histogram. The adjustments is measured in f-stops (in the [-4, 4] range) and its effect is very similar to modifying the image exposure by the corresponding number of stops (for example, stopping the aperture up or down).

The effect on the histogram can be seen in the following screenshots:

Raising the Exposure level shifts the histogram to the right while lowering the exposure level shifts the histogram to the left.

The exposure slider is used to correct the overall exposure of the image and ensure that the white is at right level. Sometimes, it's not that easy to spot overexposed pixels in an image: if you click the Alt/Option button while adjusting the Exposure slider, the canvas will turn black and Lightroom will only reveal the pixels a color channel of which is going to be clipped.

If there remain overexposed pixels after correcting the image exposure, you can try to fix them using the Recovery slider.

Recovery

After setting the overall image exposure to the right value, the Recovery slider can be used to correct the tones of overexposed highlights. If the image being corrected is RAW, Lightroom can used additional sensor data and succeed in recovering details of pixel overexposed even more than 1 f-stop.

Adjustments of the Recovery slider are made in the [0, 100] range. The effect of adjusting this slider can be seen in the following pictures:

Raising the Recovery value compresses and shifts left the highest zone of the histogram, thus revealing "lost" details that may be present in the RAW file. On the other hand, if the image being adjusted is not a RAW file, clipped channels will result in information being effectively lost: Lightroom will still compress and shift down the histogram, but it won't be able to recover missing details.

In the following pictures you can see how Recovery helps recover missing details in a picture that was intentionally overexposed by more than 1 f-stop:

You can see as adjusting the Recovery slider to +70 helps recovering details of the overexposed cloud that would have been lost otherwise. The histogram of the pictures before and after the Recovery adjustment are the following:

As you can see, the Recovery adjustment has shifted and compressed the histogram slightly to the left, leaving space to reintroduce the information recorded in the clipped highlights. The following is the histogram of a correctly exposed picture of the same cloud:

As you can see comparing the histogram of the corrected picture above with the histogram of the correctly exposed one, the slope and the profile of the two histogram in the highlights zone is very similar.

Fill Light

The Fill Light adjustment allows you the lighten the shadows of your image without affecting the black point. Adjustments of the Fill Light slider are made in the [0, 100] range, and its effect on the histogram can be seen in the following pictures:

Raising the Fill Light value has the following effect:

It slightly compresses and shifts the histogram to the right of the fill light region, without affecting the white point.
It slightly expands the histogram to the left of the fill light region, without affecting the black point.

Blacks

The Blacks adjustment is used to set the black point of the image. The adjustment is made in the [0, 100] range. Raising the Blacks value moves the black point to the right, resulting in a higher luminance level to be mapped to black. The effect of this slider mostly affects the darkest tones of the image, leaving midtones and brighter tones almost unaffected.

The effect of the Blacks adjustment can be seen in the following pictures:

Raising the Blacks value has the following effect:

It slightly expands and shifts the histogram left, without affecting the white point.
Blacks are increasingly clipped, according to the part of the histogram that's shifted beyond the black point.

The Typical Workflow

The typical workflow when adjusting the tonal scale of your image is reflected on the order of the basic tonal scale editing tools in the Lightroom user interface:

Overall exposure and the white point is corrected using the Exposure adjustment.
White point is optionally fixed using the Recovery adjustment.
The brightness of the shadows is corrected using the Fill Lights adjustment.
The black point is corrected using the Blacks adjustment.

After correcting the tonal scale of your image with the basic tools, you can fine-tune it using more advanced tool such as the Tone Curve (described in another part of this series).

Difference Between Brightness and Exposure

The Brightness adjustment allows you to correct the overall image brightness, primarily affecting the midtones. Small brightness adjustments may be necessary to correct midtones brightness after correcting the tonal scale of the image with the basic tools. Many Lightroom users wonder what's the difference between Brightness and Exposure. The main difference should already be clear:

Exposure affects the image brightness throughout the histogram and moves the white point (where highlights are clipped) shifting channel data beyond the end of the histogram.
Brightness mainly affect midtones and affects black and highlights clipping points (black and white points) to a lesser extent, try to not shift channel data beyond the end of the histogram.

To clearly understand the difference between the two adjustments, then, let's look at their effect on the histogram. The effect of Exposure has already been shown in the pictures in the Exposure section; the effect of the Brightness adjustment can be seen in the following pictures:

Brightness - Original (+50)

Brightness - +20

Brightness - +80

Brightness - +100

As you can see, modifying the Brightness level shifts the midtones region of the histogram to the right or to the left. Despite what happens when adjusting the Exposure value, however, Lightroom compresses the histogram towards the clipping points in an attempt to not modify them.

However, huge brightness adjustments end up affecting both the black and the white point: that's why you should only need slight brightness adjustment after tuning the tonal scale with the tonal scale adjustments.

Contrast

The Contrast adjustment allows you to correct the image contrast, mainly affecting the midtones. The effect of adjusting the Contrast value on the histogram can be seen in the following pictures:

Contrast - Original Histogram

Contrast - +100

Contrast - -50

The effect is the following:

The right half of the histogram is expanded or compressed to the right, depending on whether contrast is raised or lowered.
The left half of the histogram is expanded or compressed to the left, depending on whether contrast is raised or lowered.

As in the case of the Brightness control, it's important to point out that this adjustment affects midtones and can modify both the black and the white points.

Also, if you need to modify the local contrast in another histogram region, Contrast might not be the tool for you: you should have a look to Tone Curves instead.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

Adobe Photoshop Lightroom Tutorial - Part X - White Balance

2011-10-22T13:39:00.005+02:00

Part I - Index and Introduction
Part XI - The Tonal Scale

White Balance

White balancing an image means adjusting the relative intensities of the colors (in this case, of the three primary channels) to correct the drift. This process is usually performed over white or grey (two neutral colors).

Color Temperature

When adjusting the white balance of an image, you often see the concept of color temperature. This term, borrowed from Physics, describes a characteristic of light. As much as it concerns a photographer, it's sufficient to know the following:

Color temperature is usually measured in Kelvin degrees.
The lower its value, the warmer the color.
The higher its value, the cooler the color.

A photographer would often know the color temperature of well known light sources, to dial into the camera the correct color temperature in advance.

If an incorrect color temperature is used, or if the camera fails in autodetecting it, the resulting colors in the image will have drifted and will appear with an incorrect hue: typically yellow or blue depending on the side of the drift. In the following picture, you can see a strongly incorrect white temperature in a shot taken indoor with a flash:

Incorrectly White Balanced Photo

In the previous picture, the temperature of a tungsten bulb (about 2800 K) has been dialed in the camera and the shot was taken indoor with a bounce flash: you can clearly see how the hues have drifted towards the blue. Now: if you're asking why it's blue and not yellow, it's just because white balance compensates the lightning conditions used to take the shot. 2800 K corresponds to a hot color (a hue towards the yellow), so the compensation is made towards the other side (the blue).

When editing RAW files, Lightroom lets you use the Kelvin color temperature scale to set the color temperature of your image, otherwise the slider will use a [-100,100] range to adjust the temperature. Fortunately, (yet) another advantage of shooting RAW is that you can correct the white balance in post-production without affecting the image nor losing any kind of information; on the other hands, adjustments on a non-RAW file are more limited and they cannot achieve the same level of accuracy that they can achieve on RAW files. This means that, although you should always try to get it right straight out of the camera, you could always go Auto and tune it in post-production.

With Lightroom you can correct the white balance of a shot using the following methods:

You can use the color picker to sample the color of a matrix of 5x5 pixels: Lightroom corrects the white balance against the color of the chosen pixels. To use this method, you have to make sure that some neutral color is present in your shot.
You can use a preset: Lightroom offers some presets with the temperature of many well known lightning conditions (daylight, cloudy, flash, tungsten, etc.)
You can manually dial the color temperature.

In the following picture, you can see the relevant controls in the Basic panel:

White Balance Control

To use the first method, I could choose the color picker (on the left side of the panel) and choose some pixels on the images with neutral color. In this case, I remembered the door (where the two ribbons are hanging from) to be a pretty neutral light gray. If I sample those color, as shown in the following picture, Lightroom would choose a temperature of 5750 K that, indeed, is very close to the correct one (about 5500 K). The 200K difference in the resulting image cannot be appreciated very easily.

White Balance - Color Picker to Choose a Neutral Color

The resulting image is:

Correctly Balanced Photo

If you cannot use the color picker because your image doesn't contain any neutral color, you can balance it manually using your own judgement. The Temp slider is colored, as usually, with a hue scale from blue to yellow, as you can see in the picture of the Basic panel above. If you need to make the colors drift to blue just move the slider to the left and if you need to make the colors drift to yellow just move the slider to the right. The colored slider is a good mnemonic.

As I promised in the previous part of this series, we will check on the histogram what's going on to have a better understanding of each develop setting. In the following picture you can see the histogram of the balanced image and the picture of the unbalanced image with a -1000K compensation and a +1000K compensation:

Histogram of the Balanced Image

Histogram of the Unbalanced Image (-1000K)

Histogram of the Unbalanced Image (+1000K)

The first histogram is the histogram of the balanced image. As you can see, the three channels overlap very well on the right half of the histogram (if you recall what we've seen in the the previous post, Lightroom use the gray color where the three color channels overlap in the histogram). The corresponding pixels are those contained in the big area of the door, which is a neutral gray.

Pushing down the Temp slider adds a blue hue and we can see from the second histogram that the blue channel starts to expand to the right while the green and red channels start to compress to the left. On the other hand, when the Temp slider is pushed up and a yellow hue is added we can see that the blue channel starts to compress to the left and the green and red channels start to expand to the left.

Tint

As we've seen, the effect of changing the temperature is "shifting" (in reality, compressing or expanding) the blue channel apart from the other two channels. Intuitively you could argue that, since the relative position of the green and red channels hasn't changed so much, this process would be insufficient to correctly balance the white, at least in certain circumstances. In fact, you would be right. That's why there's another slider called Tint.

The tint is an adjustment used to correct the green or magenta tint of the image. Lowering the tint value raises the green tint of the image while raising the tint value raises the magenta tint of the image. Why were green and magenta chosen? Let's return to the histogram and see what happens.

The tint adjustment has an effect on the green channel very similar to the one that the temperature adjustment has on the blue channel: it expands or compresses the green channel away from the other two:

When the tint slider is moved to the left, the green channel expands to the right, compressing the blue and the red channels to the left.
When the tint slider is moved to the right, the green channel compresses to the left, expanding the blue and the red channels (whose sum is magenta) to the right.

In the following pictures you can see what happens compensating the tint of the previous image:

Histogram of the Unbalanced Image (Tint -20)

Histogram of the Unbalanced Image (Tint +20)

The tint setting is seldom used, much less than the temperature setting is. However, it's important for you to know how it works since it can really help you fine tune your images when tweaking the temperature setting is insufficient. Here's an example of a picture I took recently (contrast in the mid-tones has been increased with Lightroom):

Picture with a Green Cast

Can you see the green tint in the halo around the silhouette of the building? Well, that's a green cast that must be corrected. You can see how the tint setting has been used, adding a +17 compensation, to remove the green cast from the light. The result can be seen in the following picture:

Green Cast Corrected (Tint +17)

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

Adobe Photoshop Lightroom Tutorial - Part IX - Reading and Interpreting the Histogram - Basic Adjustments

2011-10-22T13:39:00.004+02:00

Part I - Index and Introduction
Part X - White Balance

The Image Histogram

The image histogram is a graphical representation of the number of pixels of an image with a specific luminance value. The histogram is shown in the Histogram panel that is available both in the Library and Develop modules.

Lightroom - Histogram Panel

The Lightroom histogram is the superposition of the histogram of the three RGB channels using the following color codes:

The histogram is a primary RGB color when the channel histogram of such color is not overlapping any other channel histogram.
The histogram is gray when all of the three RGB channels histograms are overlapping.
The histogram is a secondary RGB color when the two channel histograms corresponding to the primary colors whose mix is the specified secondary color are overlapping:

The histogram will be yellow when the red and green channel histograms are overlapping.
The histogram will be cyan when the green and blue channel histograms are overlapping.
The histogram will be magenta when the red and blue channel histograms are overlapping.

The histogram is an useful tool to inspect the tones used in a photo and it can provide useful insights about the quality of photo. Remember that there's not a good histogram and a bad one. The histogram is just an analytically computed representation of the colors that are present in a photo. Depending on the result you want to achieve, you can use the image histogram to evaluate whether the tones that are present in the photo are the ones you were looking for or not.

The bottom line is: the histogram is a tool and you should learn how to use it. However, use your eyes and your feelings to judge your photo, not the histogram.

The Luminosity Scale is Logarithmic

One of the keys to correctly understanding the histogram is this: the luminosity scale (the horizontal axis) is logarithmic. This may sound confusing at first but it needs not be: photographers are using logarithmic scales so often that many don't even realize they're doing so.

As we've seen in another post, the basic assumption is that our own eyes behave as logarithmic sensors on most of the spectrum range we're dealing with. If fact, you soon realize that other scales we often use are logarithmic as well: the zone system, shutter speeds and aperture values.

How to Read and Interpret an Histogram

Instead of thinking about a logarithmic scale, let's make it simple and just think about f-stops. The f-stop scale is logarithmic as well with respect to the light quantity we're letting in into our camera sensor): an f-stop increment (resp: decrement) doubles (resp: halves) the quantity of light that will hit our sensor. If you're used to think about f-stops, you can conveniently use them when reading and interpreting a luminosity logarithmic axis such as the one you find in histogram, levels and curves graphs. This way, you're life will be easy.

When looking at a graphic with the luminosity in a logarithmic scale (most of which you're using: histograms, levels, curves), just think: equal distances in the logarithmic scale correspond to an equal difference in terms of f-stops. This is also the reason why, usually, such graphics are often divided into a number of squares: to let you think about f-stops and zones. If you look at the screenshot of the Lightroom Histogram panel, you'll notice that it's horizontally divided into 4 segments of equal width. If you consider the histogram to be 8-stops wide (which it often a good approximation, but you should really be aware of your camera dynamic range), every segment is 2-stop wider. Half of a segment will be 1-stop wide. You don't need any more technicality to proceed and use Lightroom proficiently. However, the web is full of detailed information related to dynamic range, gamma correction, tone mapping and so forth.

In the following posts, when interpreting histogram to understand the effect of a develop setting, we'll always use this trick to make things easier.

Basic Adjustments

The editing workflow is where your real Lightroom artist comes out, so that there's not such a thing as a "right way" to proceed. However, the odds that you'll start using the editing controls in the Basic panel are very high, so that's the place we'll start from. Afterwards, we'll describe every panel in detail in the same order it appears in the Lightroom user interface.

The Basic panel contains the most basic image adjustments. Namely, they are:

Treatment: color, black & white.
White balance: temperature and tint.
Tone: exposure, recovery, fill light, blacks, brightness and contrast.
Presence: clarity, vibrance, saturation.

Don't be deceived by their name, though. Basic doesn't mean powerless. On the contrary, they're pretty powerful and they will be fundamental adjustments for your image more often than not.

I also found that their own meaning is deceiving and many people find it difficult to understand what their purpose exactly is. To make sense of them and unleash all of their power, we're going through a detailed explanation of what's their effect and what they're meant for.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

Adobe Photoshop Lightroom Tutorial - Part VIII - Developing Your Images, The Basics

2011-10-22T13:39:00.003+02:00

Part I - Index and Introduction
Part IX - Reading and Interpreting the Histogram - Basic Adjustments

The Develop Module

If you're still reading this series it means that:

You found it interesting, and I'm really happy to hear that this is helping you somehow.
It's now time to start editing your images.

The Develop module is the module in which most of the post-production editing will be done. The structure of the Develop module window is very easy to understand:

Most of the editing tools are located in the panels in the right palette.
The left side palette contains the panels used to manage the presets, the change history and the collections.

The Basics

One big advantage of using a tool such as Lightroom, is that it is a non destructive editing tool. What does this mean and why should it matter to you? Well, this is a very important characteristic that unleashes your creativity without ever worrying about damaging your original files.

When you edit an image in a Lightroom catalog, you're really never modifying the original file. Instead, Lightroom is tracking down each and every modification you apply and stores them in the catalog database. The advantages of this approach are manifold:

You can experiment without restraint. Lightroom is protecting your master files and you won't touch them. Ever.
You can create as many virtual copies of the master as you need, if you want to apply different settings to the same images.
Lightroom will keep track of the complete modification history of each image in the catalog. If, at a later time, you want to review it, it's there for you.
The modification history can be snapshotted at any time. If, for example, you take snapshots of an image at different stages of your work, you will be able to reload a different snapshot at any time in case you want to start over from a previous point of the image history.

Virtual Copies

A virtual copy of an image is another version of the same image to which you can independently apply a set of adjustments of any kind. Although a virtual copy is undistinguishable from a regular image, it's most often used to apply a different set of develop settings to an image.

A virtual copy of an image can be created both in the Library and in the Develop module, selecting the Create Virtual Copy item of the Lightroom Photo menu or of the image contextual menu. In the Library module, a virtual copy is easily identifiable by the "twisted corner" of its thumbnail, as shown in the following picture:

Lightroom - Virtual Copies

In the previous screenshot, the first thumbnail is a regular image, and the other two are virtual copies of the same image with (slightly) different develop settings and metadata (the first is not rated, the second has a rating of 4 and the third has a rating of 5).

You can create a virtual copy at any time: Lightroom will create a new virtual copy with the same settings as the source image at that point in time. After creating a virtual image, you can take advantage of its modification history, copied from the original file as well, to roll back to a different point in time or to select one of its snapshots (if available). And if you feel like starting over again, you can reset an image state using the Reset item of the Develop Settings submenu.

Virtual copies are an useful tool to maintain different copies of the same image without duplicating the image itself. Let's suppose that you want to maintain three versions of an image: a color one, a black and white one and a duotone one. Just create two virtual copies, apply the settings you desire and you'll be able to maintain the three images as if they were completely unrelated. Under the surface, however, Lightroom will only store one image (the master file you imported in the catalog), and you won't suffer any space consumption overhead.

History

Almost every program you use every day supports at least a basic form of command history. When you undo an action, for example, you're rolling back one step in the modification history of your file. Lightroom history, however, is different: it's persistent. This means that the history is stored alongside any other image setting and it will survive Lightroom restarts. Thus, you will be able to examine the history and roll it back at any time you wish. If you're an Adobe Photoshop user, you will recognize in Lightroom this well known Photoshop feature.

The history of an image is stored in the History panel, on the left side palette of the Develop module, as shown in the following picture:

Lightroom Develop Module - History Panel

In the previous picture, you can see an example of the history of an image. The selected item, a modification of the Tint setting, is not the top of the list but it's the third in time: this means that I'm inspecting the state of the image as it was two modification steps ago. In this case, the new value of the Tint setting is 27 and it's a +20 modification from its previous value.

If I continued to work from this state, and applied a new modification, the following history entries would be deleted and the history would start reflecting the image state since where I am.

This is the kind of situation in which you would consider creating a snapshot.

Snapshots

There are times where you where you'd like to be able to freeze an image settings at a point in time. Lightroom will let you do it and this feature is called a snapshot. When you create a snapshot, you're saving the state of the image at the time the snapshot is taken. An image, moreover, can have as many snapshots as you need and, once more, they are a feature that do not introduce any overhead. If you're experimenting different settings, as sure you will, snapshots are the quickest way of pinning those you like them and marking them as candidates for the final image version.

Snapshots can be managed using the Snapshots panel in the Develop module, as shown in the following picture:

Lightroom Develop Module - Snapshots Panel

In the figure above, you can see that the currently selected picture has got just one snapshot, called Low contrast and corrected green cast.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

Adobe Photoshop Lightroom Tutorial - Part VII - Basic Editing Tools

2011-10-22T13:39:00.002+02:00

Part I - Index and Introduction
Part VIII - Developing Your Images, The Basics

Basic Editing Tools

Before switching Lightroom into the Develop module and start using its powerful editing tools, you should be aware that basic editing tools are available in the Library module as well.

These tools are very simple and you probably won't be using them so often. However, I think it's good for you to know they exist since they can help you perform some quick adjustment in one or multiple images without leaving the Library module. These tools, especially when used with custom develop presets (more on this on the following parts), can save you a lot of work.

The Quick Develop panel (and probably the Histogram panel as well) is the panel that contains the basic editing tools available in the Library module:

Lightroom Library Module - Histogram and Quick Develop Panels

In the current Lightroom version, the Quick Develop panel will let you:

Apply a saved develop preset.
Apply a crop preset.
Apply a color treatment preset: color or black and white.
Apply a white balance preset or modify the temperature and tint incrementing or decreasing their values by fixed steps.
Modify the tones of the images incrementing or decreasing their values by fixed steps. The tonal control available are: exposure, recovery, fill lights, blacks, brightness, contrast, clarity and vibrance.

If, for example, you need to quickly adjust the exposure of an image by an f-stop, you can do it in the Quick Develop panel without leaving the library module.

You can also apply modifications to multiple images in the following ways:

You can select multiple images and apply a modification.
You can copy the modification from one image and paste it into other images using the Sync Settings button.
You can copy metadata from one image and paste it into other images using the Sync Metadata button.

When using the Sync Metadata or the Sync Settings features, Lightroom will also ask you about which metadata or settings have to be copied from the source image, as shown in the following pictures.

Lightroom - Sync Metadata Window

Lightroom - Sync Settings Window

In some circumstances, I often use these features to speed up my workflow. If, for example, I voluntarily underexposed a bunch of images by 1 f-stop to keep the desired ISO, aperture and shutter speed values (if you shoot RAW, you often can), I can correct the exposure with just one click in the Library module. If the correction looks right, I can propagate it to all of the images with just a couple of clicks. Then, I'll continue fine tuning every image using the Develop module.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

Adobe Photoshop Lightroom Tutorial - Part VI - Importing Your Images

2011-10-22T13:39:00.001+02:00

Part I - Index and Introduction
Part VII - Basic Editing Tools

Importing Your Images

The first step in your workflow with Lightroom will often be importing images into the catalog. Images can be imported from any accessible location from your operating system, including cameras connected to your computer.

To import images into your catalog, use the Import button in the lower left corner of the Library module and the import window will appear, as seen in the following picture:

Lightroom Import Window

In the left side palette, the user can choose the source folder or device from which images must be imported. Especially in the case of entire block devices or big folder hierarchies, it's important to know that subfolders can be automatically imported selecting the Include Subfolders checkbox (it appears only when a suitable source is selected). When the source has been selected, Lightroom will begin scanning it and showing previews of the images it found in the main window.

After choosing the source, you must select how to deal with imported images. Lightroom gives you four choices:

Copy as DNG: Lightroom will convert the images to DNG in a new location and add them to the catalog.
Copy: Lightroom will copy the images to a new location and add them into the catalog.
Move: Lightroom will move the images to a new location and add them into the catalog.
Add: Lightroom will add the images to the catalog.

The option you'll choose will depend on what you need to do, on how you're used to work and on the type of storage system you own. If you're importing files from your camera, you'll probably copy them into your catalog (and optionally convert them to DNG).

As I already explained in the first part of this blog post, I usually copy into the catalog the new photos and the photos I'm working on and that need to always have with me. Over time, when the images are ready to be moved to long time storage, I move them to a different folder of the catalog, usually located in another storage device.

After choosing how Lightroom has to handle the files to be imported, in the case you chose to have Lightroom copy or move them, you have got to choose their destination using the file chooser in the right column of the window.

Depending on the import operation to perform, on the right palette there will be a series of panels where you can tune the parameters of the import operation:

File Handling: This panel lets you tweak the basics of the import operation. You can choose how Lightroom will generate previews of the imported files, whether Lightroom should check for suspected duplicates not to import the same image multiple times and whether Lightroom should perform a secondary copy (a backup) of the imported imaged to a location specified by the user. This panel is always available.
Apply During Import: This is a very useful panel that lets you specify whether Lightroom should apply a develop setting and/or a metadata setting to all of the imported images. It also lets you add a set of keywords to apply to all of the imported images. This is a very handy feature, and you will get used to it very quickly. More information on develop settings will be given in the following parts. This panel is always available.
File Renaming: If you configured Lightroom to copy or move images, this panel can be used to have Lightroom rename the copied files according to the rules you establish. This panel is only available when Lightroom copies or moves files.
Destination: This panel is used to specify the target directory where files will be moved or copied to. The user can instruct Lightroom to organize the files into subdirectories according to date an image was taken. This panel is only available when Lightroom copies or moves files.

Finally, selecting the Import button will start the import operation.

Tweaking Preview Rendering

By default, Lightroom will generate minimal previews of the imported files and will only generate full screen previews when needed. While this is a benefit in terms of space consumption and CPU usage during import, whether is a good choice for you depend on how you work on your images.

In my specific case, I found that generating 1:1 previews during the import operation is beneficial when I'm editing images and continuously jumping from one to another. For the same reasons, I configured my catalogs to purge previews after 30 days.

Depending on your usage patterns, you could find a preset that's more beneficial in your case. If your goal is importing as faster as you can and you rarely inspect imported images, then the default settings or the Standard previews will be sufficient.

On the other hand, if you closely inspect most of the images you import, it might be wise to have Lightroom generate full size preview while importing your images. It will save you time and frustration and won't have to wait for Lightroom to generate a preview every time you open an image for editing.

The deal, as usual, is a tradeoff, and in this case it's a tradeoff between responsiveness and used space. If you don't mind sacrificing some disk space to store full size previews, the user experience will be much better while editing your images. Also, you don't have to wait for Lightroom to generate the previews, either. Indeed, Lightroom will first generate standard previews and you'll be able to use your catalog while Lightroom will generate the remaining previews in the background.

On the other hand, if you're running short of space, you're left only with the choice of using minimal previews and having Lightroom generate them on demand.

However, you can have Lightroom generate previews for an entire folder anytime you need it, using the Render Standard Previews and Render 1:1 Previews items into the Library/Previews menu.

Last but not least, if you want to configure the standard preview size for your catalog, you can do it in the Catalog Settings window, as shown in the following picture:

Lightroom - Catalog Settings

DNG Versus Proprietary RAW Files Formats

DNG is a file format developed by Adobe whose goal is to be a fully compatible, full featured, provider independent digital negative file format. The benefit of converting your RAW files to DNG is that, hopefully, you will be using a standard file format that's being embraced by more and more digital camera producers. You can think of DNG, for simplicity's sake, as the PDF analogous for digital cameras.

The downside of using DNG is that some information found in proprietary RAW file formats cannot be imported into DNG files and may be lost. You can search the Internet for further information about the difference between DNG files and the specific RAW file format you're currently using.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

Adobe Photoshop Lightroom Tutorial - Part V - Using Filters

2011-10-22T13:38:00.004+02:00

Part I - Index and Introduction
Part VI - Importing Your Images

Filters

As explained in the previous part, metadata is useful because it lets you organize your catalog and search for images using an incredible variety of criteria.

The Lightroom Library module is the where most of your searches will take place and it offers plenty of controls where you can start your search from.

As we've seen in the previous part, you can start a quick metadata search using:

The arrow control that is shown at the right side of a metadata value in the Metadata panel (only available for selected headers).
The arrow control that is shown at the right side of a keyword in the Keyword List panel.
Using the Attribute search bar in the filter bar.

The Attribute search shown in the previous part is just one of the kind of searches that the Lightroom filter bar will let you perform. The filter bar, in fact, is the place where you will perform any non-trivial metadata filtering.

Search criteria can also be saved for future use and quick access to frequently used search criteria.

The Filter Bar

The filter bar functionality is pretty intuitive:

It lets you build a query using the search criteria that it offers.
It applies the filter to the images contained in the currently selected folder and all of its sub-hierarchy.
It will display the results in the Lightroom main window (see Part I).

An inactive filter bar is shown in the following picture (if the filter bar is not visible, just activate it using the Show Filter Bar item in the View menu):

Lightroom Library Module - Filter Bar

The filter bars lets you build your query using criteria coming from the following sets, whose interface you can activate choosing the corresponding control in the filter bar:

Text: This interface is used to build a plain text search in one of the searchable text fields.
Attribute: This interface is used to perform a search using one of the special attribute metadata (rating, flag, label, kind) described in the previous section.
Metadata: This interface is used to perform a search using whichever available metadata field.
Saved filter: This menu is used to open previously saved filter or to save the current search criteria into a new filter.
None: the None control is just used to turn filtering off.

The following pictures show the interface of the filter bar interfaces described so far:

Lightroom Library Module - Filter Bar - Text

In the Text type search, the user can make a free text search specifying the text fields to search, the text match criteria (Contains all, starts with, etc.) and the text to search.

Lightroom Library Module - Filter Bar - Attribute

In the Attribute type search, as detailed in the previous part, the user can filter the images using flags, rating, label and kind controls, as can be seen in the previous image.

Lightroom Library Module - Filter Bar - Metadata

In the Metadata type search, the user can build a criteria made up multiple metadata filters, one per column. By default, Lightroom provides 4 columns but the user can add them or remove them at will. To change the metadata a column is associated with, it's sufficient to choose another metadata field clicking on the column label. Each column will contain the available filter values for each metadata field, depending on the values that can be found in your catalog.

Lightroom Library Module - Filter Bar - Multiple Criteria

A filter can be made up of different types of criteria. As you can see in the previous image, different types of filters can be stacked up together to build a complex query.

Lightroom Library Module - Filter Bar - Filter Menu

Lightroom provides a set of prebuilt filters with the most commonly used criteria, such as the Flagged filter, one of the filters I use most. If you want to save a commonly used search criteria into a filter, just select the Save Current Settings as a New Preset... from the filter menu and the filter will be available for future use.

A reduced filter functionality is present in the viewer bar, as it can be seen in the following picture:

Lightroom Viewer Bar

In its upper right corner, in every module where this bar is present, you can select a saved filter using the filter menu and apply a quick attribute filter using flags and ratings.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.

Adobe Photoshop Lightroom Tutorial - Part IV - Keywording and Metadata

2011-10-22T13:38:00.003+02:00

Part I - Index and Introduction
Part V - Using Filters

Metadata

Metadata simply means "data about data". In the case we're interested in, images metadata, we're referring to a set of additional data that may be attached to your images to provide further detail about them. Image metadata has been sort of standardized, and the most common sets of metadata you're probably going to deal with are EXIF and IPTC. However, depending on your gear, additional proprietary metadata can be attached to your image. Especially in the case of RAW images, for their own nature, the files must contain the settings that were active in your camera at the time of shooting, so that the RAW developing tool is able to apply them in post-production. Such metadata are highly dependent on the gear you're using and there's no easy way of providing a comprehensive list. However, common examples of such metadata are:

Detailed information about the camera and the lens you were shooting with.
White temperature.
Exposure compensation.
Flash status.
Flash exposure compensation.
Metering mode.
ISO speed.

Some metadata are meant to be provided by the user and IPTC metadata falls almost completely in this category. The user can use IPTC fields to provide additional information about a photography such as:

General information about the image (title, caption, etc.).
Information about the image content (subject, models, etc.)
Information about the image location.
Information about the image author.
Information about the image copyright status.

As far as it concerns image organization, metadata is a powerful tool to help you organize and filter your data. Lightroom gives the possibility of performing searches using whatever metadata header your images may have. That's a pretty useful tool to build your smart collections or dig into your gigantic catalog looking for a specific photo whose location you cannot remember.

Very often, just a few metadata helped me restrict the search scope to a small bunch of them. For example, the camera I used, the lens and the focal length are one of the first criteria I use when digging into my catalog. And if this is not sufficient, then I rely on keywords, as explained in the next sections.

To inspect and modify an image metadata, you can use the Metadata panel, a screenshot of which is shown in the following picture.

Lightroom Library Module - Metadata Panel

If you're interested in a specific set of metadata headers, such as EXIF or IPTC, you can select it in the listbox control in the upper left corner of the panel (in the image above the EXIF set is chosen).

You will be able to introduce custom values in writable metadata headers, such as IPTC. If you want to quickly filter your images using a specific metadata value, you can use the arrow control shown on the right side of the corresponding header. This control is only available on selected metadata headers.

The Importance of Well Known Metadata Headers

Metadata is important because you can take advantage of it at any stage of your workflow, without the need of artificially tweaking it to your advantage unconsciously introducing redundancies and potential inconsistency problems. Metadata can be used, for example:

To organize your images: location or subject metadata can be used to search and build collections.
To edit your images: camera and lens information can be used to apply specific corrections, such as applying camera calibration profiles or lens correction effects.

I've seen many people manually organizing their catalogs duplicating information that could easily be stored in commonly used metadata headers such as the IPTC location headers. There's little use in creating custom keywords to do such a task:

If there's a standard header, just it. Chances are your tool will give you additional feature built around it than what you can do with a plain keyword. A tool could, for example, build a map based on location headers or use the copyright status of your image to choose a suitable watermark, while it could hardly do so using your own custom keywords (that it's unable to interpret).
Custom keywords can be confusing, at times, since they're only labels.

My advice is: take your time exploring EXIF and IPTC headers and learn what they're meant for. They're there for a good reason.

Custom Metadata

Well known metadata such as EXIF and IPTC are such because they're the most widely used metadata headers out there. However, they're not sufficient for most practical organization purposes and you will rely on applying your own (custom) metadata to your images.

Lightroom lets your add the following kind of metadata to your images:

Flags: flagged or rejected.
Colored labels: 5 different colors currently available.
Ratings: a rating from 0 to 5.
Keywords.

Flags, labels and ratings are very intuitive tools and are distinct in that they have a direct effect on how Lightroom shows your image thumbnail in the library module.

Lightroom Library Module - How Some Metadata Is Shown in the User Interface

In the previous image, you can notice the following:

The first two images are flagged, as indicated by the white flag icon on the upper left corner of each thumbnail.
The first image was rated with 4 stars and the second with five, as indicated by the black star icons just below the image thumbnails.
The third image was flagged as rejected, as indicated by the black flag icon on the upper left corner of the thumbnail. Additionally, Lightroom grays out the thumbnail of rejected images, making easier to quickly identify them into the film strip.
The fourth image as been labelled with a yellow label, as indicated by the yellow icon on the bottom right corner of the thumbnail and by the yellow shade of the thumbnail itself.

This metadata is very useful in your everyday workflow because they let your rate your image, reject shots you don't like and flag the shots you are interested to. Lightroom also comes with prebuilt filters that let you quickly filter your images using these metadata.

Lightroom Image Module - Attribute Filters

As you can see in the previous screenshot, the Lightroom filter bar lets you quickly filter in a graphical and intuitive way using the metadata we just talked about:

Using the three flag icons, you can filter flagged, unflagged and rejected images.
Using the five star icons, you can filter images with the specified minimum rating.
Using the seven colored box icons, you can filter images using the specified colored label.
Using the three kind icons, you can filter images based on their types: images, virtual copies and videos.

Keywording

When you need more than all of what we previously described, Lightroom lets you apply custom keywords to your images. Keywords are just text labels that you can attach to your images and every image can have as many keywords as you'd like.

I use many kind of keywords:

Keywords that specify the image type: landscape, portrait, etc.
Keywords that specify the kind of event: holiday, birthday, wedding, etc.
Keywords that specify the kind of post-processing I applied: levels, orton, crop, black and white, duotone, etc.

The keywords you choose to use are up to you, as well as it's only the user who decides how he wants their images to be organized.

The most important advice I can give about keywords is: being consistent and coherent. I surely am about the keywords I use and over the years I've built a keyword dictionary I'm pretty comfortable with. There's no use in using keywords you won't remember. I'm almost always able to figure out which keywords I might have applied to the picture I'm looking for simply remembering how it looked like, when it was taken or the kind of event it represents.

My advice here is: experiment with keywords. At the beginning you're probably going to refine your dictionary very often. Over time, however, you will get used to a well known subset of keywords you will be using over and over again.

Lightroom Library Module - Keywording

The Keywording panel is used to manage the keywords of your images. You can add keywords simply by typing them in the text box shown in the previous figure. Lightroom, using your keyword history and the keystrokes, will help you quickly identify existing keywords showing them in a combo box. Also, based on the keywords already applied to the image and your keyword history usage, will try to help you suggesting candidate keywords in the 3x3 matrix labelled Keyword Suggestions that you can see in the picture.

If you're a keyword power user and your dictionary is made up of hundreds of words, you can organize them in subsets. You can select the subset you're interested to in the Keyword Set combo box and Lightroom will show them in the 3x3 matrix just below it, as seen in the previous picture (in that case, the automatically built Recent Keywords set is shown).

Managing Your Keywords

Keywords themselves can be organized in a tree structure that's handy to use especially when your dictionary is becoming pretty huge.

Lightroom Library Module - Keyword List Panel

The Keyword List panel is used to filter, create and organize your keywords. As you can see in the previous screenshot, the activity and the animal keywords are parent keywords that have some children. Clicking on the white triangle on their left will open their subtree and will show you their sub-hierarchy.

This panel can also be used to know how many pictures are labelled with a specific keyword, as indicated by the number on the right side of the keyword itself.

To quickly filter the images based on a specific keyword, you can use the right arrow icon that appears when hovering your mouse pointer over them.

If you want to help me keep on writing this blog, buy your Adobe Photoshop licenses at the best price on Amazon using the links below.