The previous installment of this post, Lightroom Adjustments: Exposure vs Brightness was featured on the facebook Lightroom page and brought a very large number of visitors to this modest site. Over 5,000 visits and more than 8,000 page views were exceptional numbers for Kept Light. Also, comments and questions both on this site and on facebook nudged me to continue the investigation and focus on color shift during the exposure and brightness adjustments.

I made a color and gray scale ramp in Photoshop with carefully applied colors and grays. The purpose was to see if the saturation or the hue would change differently under different adjustments. The sample was imported into Lightroom and I took careful measurements of each patch in Lightroom. The top row of numbers in each cell represent Photoshop RGB values in which each color changes from 0 to 255. The second row of numbers are the Lightroom measurements where each channel has percentage values that range from 0 to 100. The first thing that is very easy to observe is that Lightroom color model is a good deal different from the Photoshop RGB model. In the Photoshop color formation there is a clearly visible patterns, like 0-0-255 and 0-255-0 which are linear relationships. Increasing the red from 127 to 255 will max that channel and double the Red value. The same behavior will be observed on the green or the blue channels as well. In Lightroom color model this kind of pattern is simply not there; different hues are formed with a different formula as you can see in the percentage numbers. The only place where the pattern based behavior is visible is on the gray scale patches.

The second thing that is worth observing right away is that the luminosity values for each color and each patch are interpreted differently in Photoshop and Lightroom, further supporting the idea that the color models are substantially different. Take a look at the two gray scale versions of the target done in Photoshop and in Lightroom by reducing the saturation to zero. You will notice that the gray values coming from Photoshop produce the same tonal values for patches where the amount of R, G and B are similar like 0-0-255 and 255-0-0 producing identical gray tones. The situation is a good deal different in Lightroom. When desaturated, the color patches show different levels of brightness that will probably explain some of the later observations. In other words, “greens” are “brighter” than “reds” which are “brighter” than “blues”.

I proceeded to apply one adjustment at a time, exposure -2, -1, +1, +2 and brightness -100, -50, +50,  +100 and recorded the Lightroom values in each square on the test chart. These numbers along with the original readings were entered into an Excel spread sheet. Since I wanted to see the “change” in the value of each square I calculated the difference between the adjusted values and the original values to produce the bar charts you will see below. What is not easy to see in the bar charts will be much easier to see when you look at the test image with each adjustment applied.

Here are the Excel produced charts which are kept to the same axis scaling so as to avoid perceptual distortion:

Now take a look at the color patch sample with each of the adjustments:

The last set of images are quite informative, albeit in a subjective way. It is easy to see that “darkening” an image using exposure or brightness is a forgiving adjustment regardless of the adjustment tool used. However, when “brightening” the image, exposure adjustment creates serious hue shift in greens and blues. This is particularly easy to see in the fourth image, Exposure + 2. On the other hand, the brightness adjustment retains the hues fairly faithful to the original values and displays a more “expected” result. None of the brightness adjustments, under or over exposing the image causes any subjectively visible hue shift in any of the patches.

Not knowing the actual color model used in Lightroom it is difficult, even improper to make a statement about the cause of this behavior. However, based on my observations of the channel value changes as one of these sliders are moved I can say this:

The exposure adjustment moves the values in the channels reasonably close steps. Consequently, it quickly runs out of room on a channel where the starting value is high to begin with. After reaching 100% on that channel, Lightroom continues to increment the other channels to provide the exposure increase. On the other hand, the brightness slider is far more judicious in its steps and somehow manages not to run out of head room in any of the channels as the level of brightness is increased. Consequently, it avoids the hue shift that quickly emerges in the exposure adjustments. The reason why neither adjustment causing hue shifts in “darkening” the image must have to do with the ample head room in each channel for decreasing values.

The empirical observations and visual cues and clues indicate that if a photograph needs serious upward adjustment of the “darkness” the brightness slider may be a better starting point. (I used “darkness” to avoid referring to either of the adjustment slider directly.) For modest adjustments, or to darken the image either slider seems to produce similar results. I would liken the brightness slider to the behavior of a curves adjustment layer in Photoshop after changing its blend mode to “Luminosity.” In fact, if an image needs that much adjustment in the upward direction making that adjustment in Photoshop may offer additional flexibilities. In addition to changing the blend mode of the curves to luminosity I can also use the “blend if” sliders to further adjust how each channel may be affected by adjustment or use layer masking and the like.

It would be awfully good of someone who knows the inner workings of Lightroom to provide better explanations of these adjustments. My curiosity brought me up to this point. I hope that this installment provides a little better understanding of the color shift behavior others seem to allude but not explain. Here at least you have visual clues as to the impact of these adjustments on color shift and some measurement results charted.

After further studying the behavior of the exposure and brightness sliders and discovering how strong upward exposure adjustments can cause serious color shift, I am modifying my workflow as shown below. Instead of relying mostly on exposure adjustment I am beginning to think that brightness adjustment is a more stable tool. On a photograph +2 exposure or +150 brightness produce almost identical results the latter being slightly more restrained. Ideally, this much adjustment should not be necessary, but in a pinch try the brightness firs. Now I understand better why Lightroom “Auto” tonal adjustment almost always uses the brightness slider.

I have been using Lightroom since its original public beta before version 1 was released. It has become an indispensable tool in my workflow like many other photographers. It offers a very good set of tools for photographers in a very usable interface. Those of you who go back that far may remember another product before Lightroom was even announced, Raw Shooter Essentials and Professional. The Essential was free and the Professional was worth every penny I paid for it. Adobe thought likewise and purchased the company and its technology along with it. Several tools in Lightroom, later in Photoshop are descendent of Raw Shooter series. The most notable ones that are visible outside are Recovery, Fill Light, Vibrance, and Clarity sliders. Along with these, I would not be a bit surprised if the entire “Basic” group is a descendent of RSE including brightness, blacks, and exposure. Interestingly, I have found the information on the “basic” group the most spotty and “soft” in presentation and explanation. Generally, explanations go like this “brightness is kind of exposure control but leaves the end points alone”, “it is a kinder and gentler exposure slider”, and so on. There are many discussions on variety of forums and you will read a variant of these explanations peppered on the Internet. Even Martin Evening in his quite encyclopedic volume on Lightroom does not provide a fully satisfying explanation of how the Exposure slider adjustment differs from the Brightness slider adjustment.

To better understand the behavior of these sliders, which seem to do very similar but not identical things, I decided to study their behavior on an artificial gray-scale ramp. In Photoshop, I created a 1200×1200 blank image and filled it from left to right with a gradient map going from black to white. To make reading values more consistent, I posterized the gradient fill with 16 steps. After importing the PSD file in to Lightroom, I took RGB readings from each strip and recorded them on each strip in Photoshop. The resulting file had the steps all identified as Lightroom saw the RGB values. Since they were all identical, I did not repeat the numbers for R, G, and B channels.

I created an Excel spreadsheet with the original measurements as the base line. Then proceeded to increase the Brightness adjustment in three large steps of 50, 100, and 150. After each adjustment, I measured the value of brightness (RGB values) on each step and recorded along the base line measurements. Then I went in the negative direction, -50, -100, and -150 and recorded the brightness values. The intention here was to measure the change affected by each step of adjustment on different values of grays.

Next, I zeroed the Brightness slider and changed the Exposure slider in +1, +2, +3 and -1, -2, and -3 settings while measuring and recording the resulting values in each step of the gray-scale ramp. I charted the observed differences in tonality in the following graphs, one for Brightness adjustments and one for the Exposure adjustments.

Now, let us take a look at the charts and see what we can observe. Clearly, the overall behavior of both sliders seem to be similar. However, some important points to note are:

1. None of the settings produce a linear response, the effect starts low, peaking at some point, and then diminishing again
2. When increased, Exposure seems to affect the shadows more than Brightness
3. When decreased, Brightness appears to impact the highlights more than Exposure
4. Since the end points are black and white they do not register any change
5. Reducing Brightness seems to be a better way to tame the highlights and high values
6. Increasing Exposure seems to be a better way to deal with opening the shadows and low values
7. The effects mentioned in 5 and 6 are most pronounced with extreme adjustments, probably not used often
8. Some settings produce nearly identical results, see Exposure = – 1 and Brightness = -50 graph

In practice, neither adjustment will likely be used alone. When used in combination with Blacks, Fill Light, and Contrast the results can vary significantly depending on the choice of tools. Real images bring their own problems that may stem from using one adjustment over the other. So, a generalized statement on which tool to use is difficult to make. However, the shape of the histogram will likely give clues as to the best starting point. The Lightroom’s built-in “intelligence” seems to favor using Brightness more than Exposure when the “Auto” option is used, and I have not yet seen only one slider adjustment being sufficient.

Here is my workflow for tonal adjustments: (Modified after the follow-up analysis of how these adjustments affect color shift)

1. Set the “appropriate” white balance (I am avoiding “correct” since the WB depends on context and sensibility of the photographer)
2. Set the “White” point, the highlight end using Exposure Brightness; remember not every photograph has a “White” point in Zone 9, don’t push it
3. Set the Black point using the “Blacks” slider; these two adjustments will likely provide the necessary contrast
4. If necessary, adjust the mid-tones with the “Brightness” Tone Curve, Exposure, even brightness
5. If there are blown highlights, gently introduce “Recovery”
6. If there are blocked shadows that need a hint of detail, use the “Fill Light” slider
7. For finer tuning, use the Tone Curve adjustment either in parametric or point curve mode
8. Use the HSL panel, starting with the Luminosity group and fine tune the brightness of each channel as well as saturation as necessary (easy, a little goes a long way!)

Here are some more graphs each showing a pair of Exposure-Brightness adjustment results for easier comparison. Of course, some of you may be wondering why I chose 50 unit increments for Brightness and 1 stop increments for Exposure. I have no scientific reasoning behind it other than I wanted to divide the Brightness and Exposure ranges into 6 and these numbers seemed “reasonable”. Also look at the sample photographs resulting from different adjustments. You will be hard pressed to tell the difference in some instances (well, most instances) except the “Auto” setting which I left without further tweaking. As you see, at least depending on the image, it is possible to create virtually identical results with significantly different adjustments.

Although this post has not reached a definitive conclusion on the behavior of these two adjustments, it at least has provided you with a carefully measured results and how they compare. I am sure you can develop your own conclusions that will work for your workflow.

Photographers and programmers have been trying to expand the capabilities of Lightroom by developing plug-in modules for it to perform functions that are not available in the core program. I will share several with you in this post. What you will read in this post will be the tip of the iceberg as there are many more such add-on modules, I will only share those that provide functions that I consider of use. Furthermore, this review excludes paid plugins from vendors like onOne, Nik, SlideShow Pro, and others. What you will find here are plugins that are free to try, and donate to own. The developers put many hours to developing these programs and deserve to be compensated no matter how small or large you decide to donate.

LR/Enfuse

I first tried Enfuse, an image stacking software add-on, several years ago when it was an experimental piece. After a few tries, I decided to put it aside and then totally forgot about it. Recently I saw it mentioned in a book Night Photography by Lance Keimig (very good book, by the way) and tried it once more. The Lightroom plugin that makes using Enfuse much easier is from Photographer’s Toolbox and the use is fairly straight forward. Below are three photographs that show the input, the first two, and the output from LR/Enfuse. The plugin is donationware, you are free to try it with some limitations. I sprung for the donation and got the fully functional version. It works as advertised. I took the two shots with a hand-held 5D Mark-II in a children’s museum in Massachusetts. The result is akin to HDR processing without the lengthy process and unsightly artifacts. I like that.

LR/Mogrify 2

After my Exploring Lightroom presentation a short while ago at the Photographic Society of RI, a friend asked if Lightroom did have the facility to add a watermark as he exported images for sharing on the Web. I knew the print and slide show modules had that feature but was not sure if the export workflow had that built-in. It turns out that Lightroom 3 added that to the export facility. That said, if you want to add more elaborate watermarking or to add a frame on the photograph, LR/Mogrify 2 seems to be the tool to use. Its installation is a bit involved, so read the instructions on the site and follow them carefully. The opening image was processed with LR/Mogrify 2 with the bluish border and the text in the center. It can be positioned depending on your needs and it can contain EXIF data as you see here.

Elemental

This could be a very useful plugin for those who use Lightroom and Photoshop Elements. Although Lightroom has a very tight integration with Photoshop, it can only pass an image to edit to other programs. The promise, and the premise, behind Elemental is to offer a similar tight integration with Photoshop Elements, like opening multiple files as layers, or photo merge. Since I do not have Elements, I cannot tell you how well the integration works, but the free trial should encourage Elements users to give it a go. It may be a satisfying experience.

GPS-Support

Some cameras have built-in GPS facilities that add location data to each image identifying the exact location where the photograph is taken. My cameras do not have that and some photographs will benefit from having geoencoding data. This plugin, GPS-Support Geoencoding, allows the user to manually add location data. It interfaces very nicely with Google Earth and takes the coordinates of the displayed location. The embedded geoencoding data is not visible under some circumstances which are explained in the documentation on the Web site. With many cell phones having built-in GPS may allow users to take a few photographs at certain places will acquire the GPS location data for use in this plugin.

Metadata Wrangler

Each image exported to various formats contains surprisingly rich metadata. Sometimes this is useful at other times it may reveal information you may not want to reveal. The two photographs that accompany this segment are identical in every respect except for the amount of metadata. Take a look at the first image’s metadata, I am sure you will be surprised at the length and detail of information. Now, take a look at the second one’s metadata which was passed through the Metadata Wrangler, removing much of the information. You decide how much to keep and how much to discard.

In addition to these, you may consider looking into plugins for Proshow Producer or Gold for Lightroom, or Photomatix plugin if you use these software, they are free to download but do not do much if you don’t have the host software that will interface with them.

There are also Lightroom presets that you can download from different sources. onOne Software offers presets for Lightroom, and there are many others on the Adobe Lightroom Exchange. Visit and look around.

You may have your favorite Lightroom plugin, share it with everyone by posting a comment to this post.

Apparently others missed the same capability that onOne software collaborated with Scott Kelby to develop a tool called Perfect Layers. It is not available yet, but you can download a public preview from onOne software Web site and give that a try, it works with Lightroom or Aperture. I downloaded and experimented with the software. It works as intended, and for many users it may mean less need for Photoshop and money saved from that. As a Photoshop user, I did not see much benefit in Perfect Layers as I can easily open the file or files in need of layers-based adjustments in Photoshop. For many other users who do not have Photoshop and try to do everything in Lightroom, Perfect Layers can be a very useful tool indeed. The process is an automated export to and import from Perfect Layers, so the functionality is not directly added to Lightroom. The round trip workflow is easy and straight forward. Some sophisticated blending mode tools, like “blend if” sliders, channel selectors are not there but this is a preview version and some of these features may actually end up being included in the final release version.

When released in mid 2011 Perfect Layers will be priced around $160. If you are seriously interested in the software, you may take a look at a special offer for the Perfect Photo Suite 5.5 at $299 after a rebate. The owners of Perfect Photo Suite 5.5 will apparently receive Perfect Layers free when it becomes available. Perfect Photo Suite 5.5 includes several potentially useful tools in one bundle. Considering the $499 MSRP, $299 after rebate looks downright seductive. The rebate is available only until April 30, 2011, so if you are interested you may need to act fast.

When viewing the presentation, advance by clicking inside the slide. You can maximize the presentation by clicking on the maximize icon, far right on the navigation bar.

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