- Tone Mapping
- Color Correction
- Color to Black-and-White Conversion
- Maximizing Image Detail
This chapter is from the book
This chapter is from the book
This chapter is from the book
Color Correction
It can be pretty difficult to separate tone adjustments from color-correction techniques. The tone-mapping examples all resulted in changes to color, but instead of altering the color itself, they altered the tone of the color. The following color-correction examples dwell on substantial changes to the chromatic nature of the images. Yes, some tone mapping is involved, but it’s the subtle or not-so-subtle changes in color that are emphasized.
White balance (global)
Unless you want to run around with a color temperature meter to accurately measure the actual white balance, you’ll just have to rely on your camera ... which can sometimes be a bit of a problem. Most of my cameras record reasonable white balance information in the EXIF metadata that Lightroom and Camera Raw can make use of reasonably well. However, my Phase One 645DF camera and back are less good. I generally set WB to the standard Daylight on the camera back and just roll with it, knowing I’ll be spending time adjusting after the fact. Yes, if accuracy is needed, I’ll use the ColorChecker Passport to make the adjustments both more technically correct and easier to accomplish, but that’s a bit of a pain in the field.
The example I’m showing here is of an Icelandic horse shot in, well, Iceland. I had the camera back set to Auto White Balance (my bad). The lighting was overcast with a touch of volcanic ash in the air from the eruption of the Eyjafjallajökull volcano. Figure 4.24 shows the original As Shot WB and the Lightroom default Daylight WB.
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AS SHOT WB TEMP 4900 K, TINT –17
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From the Daylight preset, I felt more warmth was needed (which is often the case unless you’re looking for a cold effect). I adjusted the WB to 6500 K and a +17 Tint, as shown in Figure 4.25. The results of the white balance were fine, but the overall tone mapping was off, so the second figure in Figure 4.25 shows the global tone and color corrections applied.
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WB ADJUSTED: TEMP 6500 K, TINT +17
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GLOBAL TONE ADJUSTMENTS: EXPOSURE +0.40, CONTRAST +40, HIGHLIGHTS –32, SHADOWS +10, WHITES –58, BLACKS –9, CLARITY +64, VIBRANCE +45
Figure 4.25. Adjusting the white balance and global tone and color adjustments.
The tone mapping consisted of adjusting Exposure and Contrast higher, Highlights lower, Shadows up, and Whites and Blacks down. I also added a healthy dose of Clarity and Vibrance. In the HSL panel, I adjusted the Yellow Hue to +17 and adjusted the Orange and Yellow Saturation both to +9.
You might have noticed that I flipped the image horizontally. I decided I didn’t really like the horse looking off to the right because I thought it drew the viewer’s eyes off to the right and off the image. You can decide for yourself if you agree. (My wife and daughter disagree, but I’m the one who makes the final decisions—at least when it comes to my photographs!)
The image still needed some additional local adjustments. I used three Graduated Filters to darken the top and left edge of the image. The top gradient was a simple –0.50 Exposure adjustment. The second was an additional –0.75 Exposure adjustment. I used two separate gradients to vary the gradient slope. (It would be nice to be able to do that in a single gradient, but there’s no way to edit the gradient slope in a single Graduated Filter.) The gradient on the left was a minus Exposure and a plus Highlights to flatten down and darken the left side of the image.
Because the overall Graduated Filters darkened down the mane of the horse too much, I came back with an Adjustment Brush to relighten areas of the mane. The mask in Figure 4.26 shows the Graduated Filter and the Adjustment Brush mask.
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GRADUATED FILTER ADJUSTMENTS
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ADJUSTMENT BRUSH ADJUSTMENT MASK: EXPOSURE +50, HIGHLIGHTS +29
Figure 4.26. The local tone adjustments.
I like this image in color a lot. However, later in this chapter, you’ll see that I also experimented with the image in a toned black-and-white image (see the “Color to Black-and-White Conversion” section). The final color image is shown in Figure 4.27.
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Figure 4.27. Final Icelandic horse adjusted image.
White balance (local)
A global white balance correction may be fine most of the time, but sometimes you may need to modify the white balance locally. There are several ways, but I find the most direct way is to paint in a local adjustment with the Adjustment Brush. For this image of a man walking with his burros in San Miguel de Allende, Mexico, the default white balance was too cool. I wanted a very warm look. Figure 4.28 shows the default white balance and the adjusted result. The image was captured with a Panasonic LUMIX HG2 camera with a 14–140mm lens at ISO 400.
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DEFAULT AS SHOT WB: TEMP 5750 K, TINT +7
WB ADJUSTED: TEMP 7000 K, TINT +9 GLOBAL TONE ADJUSTMENTS: EXPOSURE +0.10, HIGHLIGHTS –42, SHADOWS +62, WHITES –20, BLACKS –20, CLARITY +60, VIBRANCE +40
global tone aDjustments: exposure +0.10, hIghlIghts -42, shaDoWs +62, WhItes -20, blacKs -20, clarIty +60, VIbrance +40
Figure 4.28. Comparing the default As Shot and adjusted WB.
In the default white balance, you can see the street in shadows looks cool. Making a strong warm adjustment had a global impact on the street that I didn’t like. I made two Adjustment Brush adjustments aimed at cooling down the shadows and lightening the reflections in the wet part of the street. The adjustments cooled down the street color, and I added a plus Shadows adjustment to lighten the areas a touch. Since I used a strong lightening effect on the Shadows, I also included a plus Noise Reduction. To lighten the wet area, I added a strong plus Exposure and a milder plus Shadows and a plus Clarity adjustment. Figure 4.29 shows the two Adjustment Brush masks.
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MASK FOR THE SHADOW COOLING: WB TEMP –70, TINT –11; SHADOWS +46; NOISE REDUCTION LUMINANCE +29
MASK FOR THE WET AREA LIGHTENING: EXPOSURE +2.49, SHADOWS +20, CLARITY +39
Figure 4.29. Local adjustments for white balance cooling and lightening.
The result of the local white balance cooled the shadows on the street a bit more than the original As Shot WB, but it gave me the warm/cool lighting I was looking for. For the final image, I added some additional Adjustment Brush adjustments. I added a mask to darken the white top of the building in the background primarily using a minus Highlights adjustment. I also painted in a pretty substantial tone adjustment on the front of the walking man. I also added a +51 Noise Reduction Luminance. I had already dialed in a +38 Noise Reduction Luminance globally, so the local adjustments added additional Noise Reduction strength. Figure 4.30 shows the final result.
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Figure 4.30. The final image of a man walking his burros.
Color curves
The new addition to the Tone Curve panel provides the ability to use per-channel color curves for color correction. You can use it for cross-curve correction or creatively. I’ll show you how I use it creatively. The image shown in Figure 4.31 was captured with a Canon EOS 1Ds Mark II camera with a 24–70mm f/2.8 lens. It was shot during my first trip to Antarctica while sailing into the Lamaire Channel (which is often referred to by its nickname “Kodak Gap,” because it’s a frequently visited destination on cruises). I took this photograph before sunset, which lasts about four hours that far south.
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DEFAULT AS SHOT WB TEMP 6100 K, TINT –1
Figure 4.31. The default rendering of the Lemaire Channel at 12:28 a.m., just before sunset.
I adjusted the WB from the As Shot setting and increased the global Exposure, Contrast, Highlights, and Shadows to adjust the tone mapping. I added Clarity and Vibrance. Finally, I added an Adjustment Brush mask with adjustments for the center of the island and increased Exposure, Contrast, Highlights, and Shadows to bring out the tonality of the hill. The strong Clarity was to really bring out the textural detail. Figure 4.32 shows the mask and the locally adjusted results.
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ADJUSTMENT BRUSH MASK FOR LIGHTENING THE HILL: EXPOSURE +0.14, CONTRAST +13, HIGHLIGHTS +25, SHADOWS +25, CLARITY +60
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RESULTS OF THE LOCAL AND GLOBAL ADJUSTMENTS: WB TEMP 5500 K, TINT +10; EXPOSURE +0.45; CONTRAST +20; HIGHLIGHTS +11; SHADOWS +16; CLARITY +30; VIBRANCE +20
Figure 4.32. The adjustment mask with the global adjustments result.
I wanted to warm up the highlights while cooling down the shadows. To do this, I used the channel curve in the Point Curve of the Tone Curve panel. Instead of trying to write down the curves I adjusted, I’ve resorted to showing you the channel curve adjustments that were made and the result of the changes to the image. Figure 4.33 shows the four points I adjusted.
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RED CHANNEL HIGHLIGHT POINT
RED CHANNEL MIDPOINT
BLUE CHANNEL HIGHLIGHT POINT
BLUE CHANNEL MIDPOINT
Figure 4.33. The color channel points adjustments.
To achieve the results I wanted, I placed a point at about the ¼ position in the Red channel and raised it to make the highlight gain red. You can see the input/output levels in the figures. The midpoint in the Red channel wasn’t so much to change the color but to hold it. You may need to add a “blocking point” to keep the Bézier curve behavior from impacting additional levels. I added ¼ tone and midpoints to the Blue channel as well. The addition of red and yellow made the highlights warmer. You’ll note that in the blue midpoint, I did allow some yellow to extend down into the midtones.
The final results are actually more along the lines of what I think I remember from being there. This is one of my favorite images from all three of my Antarctic trips—in large part because of the light and the experience of getting to engage in the act of producing major gigage! Figure 4.34 shows the final result.
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Figure 4.34. Final image of the Lemaire Channel sunset, color corrected using color curves.
Color split toning
Given my druthers, I would rather shoot a sunset than a sunrise. Why? Well, for one, you don’t have to get up early to shoot a sunset. Plus, shooting a sunset allows you to set up in the light. A sunset also gives you plenty of warning regarding weather—if the light is going to suck, you know it in plenty of time to go to dinner.
However, if you fly to London and then drive to Edinburgh to do some shooting with a friend, you aren’t going to be sleeping in late in your hotel room, are you? I didn’t. I went to Scotland with my good friend and colleague Martin Evening. Martin wanted to do a dawn shot from Calton Hill in central Edinburgh. We woke up around dawn and found that the weather wasn’t ideal. But in for a penny, in for a pound, we went to shoot.
We didn’t really have a spectacular sunrise. Clouds to the east made sure of that. But there’s an old saying in Scotland: if you don’t like the weather, wait five minutes—it’ll change. I later found that isn’t always true, but the clouds did break and we got some shots. The image I’ll be using to show color split toning is of the Dugald Stewart Monument, a memorial to the Scottish philosopher and mathematician Dugald Stewart. The capture shows that a tiny bit of sun was peaking out of the clouds and, although it was okay, I thought I could make it better in post. Figure 4.35 shows the image at default and with global tone and white balance adjustments.
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DEFAULT RENDERING WITH WB AS SHOT TEMP 5400 K, TINT –2
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GLOBAL IMAGE ADJUSTMENTS: CONTRAST +35, SHADOWS +42, BLACKS –13, CLARITY +32, VIBRANCE +33
Figure 4.35. The default and global image adjustments.
I adjusted the WB from the As Shot setting to warm the image. The main change in the tone was to increase Contrast and add a plus Shadows and minus Blacks to modify the tone mapping. Yeah, I added Clarity and Vibrance—big shock, huh? I also applied the Lens Correction to get rid of barrel distortion found on my Canon EF 28–135 lens. Because I had set up the camera level, I didn’t need to worry about keystone correction.
The image needed some local “enhancements.” I used the Graduated Filter to darken down the sky (a –0.89 Exposure) and the Adjustment Brush to lighten the center of the monument and darken some of the bright building in the background. I painted in a plus Exposure adjustment on the monument to lighten the columns and a minus Exposure and Highlights adjustment on the background using the Auto Mask to darken the bright buildings. Figure 4.36 shows the two Adjustment Brush masks.
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MONUMENT LIGHTENING MASK: EXPOSURE +0.99
BUILDING DARKENING MASK: EXPOSURE –0.89, HIGHLIGHTS –48
Figure 4.36. Adjustment Brush masks.
To finish off the color adjustments, I used a Split Toning panel adjustment to warm up the highlights and cool down the shadows. I could have done this using color curves, but to be honest, split toning is easier and quicker if you don’t need to have specific color adjustments (and it gives me a useful example of using split toning). I selected a warm color for the highlights and a cool color for the shadows. In this case, I didn’t need to modify the Balance split point. Figure 4.37 shows the separate highlights and shadows color adjustments.
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WARM COLOR FOR THE HIGHLIGHTS: HUE 48, SATURATION 48
COOL COLOR FOR THE SHADOWS: HUE 228, SATURATION 30
Figure 4.37. Comparing the color effect of the highlights and shadows regions of the Split Toning panel.
When you combine the global and local tone corrections with the split-toning effect, the end result seems like a glowing sun was lighting up the Dugald Stewart Monument that morning in Edinburgh. It was ... I just sort of helped the shot along. Figure 4.38 shows the final image.
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Figure 4.38. Early morning light (enhanced) from Calton Hill overlooking Edinburgh.
Color gradients
The Graduated Filter is a useful correction tool, but not just for tone adjustments. You also can use it to alter and adjust the existing colors of an image. For this particular shot at Arches National Monument, taken well after sunset, I wanted to bring out the warmth of the glow on the horizon while deepening the blue color of the sky. I took this on the same day I shot the Turret Arch image. Martin and I had started driving back to the motel and came upon this scene. We grabbed our cameras and flashlights (it was really dark by then) and set up to shoot a few frames. This image was shot at ISO 50 with a shutter speed of 3 seconds with the P65+ camera back. Nice, but not what I remember seeing (or thought I saw). Figure 4.39 shows the image before the color corrections. Oh, and if you’re wondering, I didn’t bother to use any Clarity—I tried, but it didn’t do anything (although Vibrance was set to +28).
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Figure 4.39. Moon setting in Arches with post-sunset glow.
I decided to use two color gradients: a warming one to help the glow and a cooling one to cool down the sky. The gradients were applied as a color tint, but the saturation of the colors I used also strongly increased the overall saturation of the colors. Figure 4.40 shows the two gradients applied individually to show the unblended adjustments. Figure 4.41 shows the results of both gradients applied together.
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WARM GRADUATED FILTER APPLIED
COOL GRADUATED FILTER APPLIED
Figure 4.40. Applying a warm and a cool Graduated Filter.
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Figure 4.41. The combined warm and cool gradients applied.
Once the two gradients were combined as shown in Figure 4.41, the dark blue sky and golden horizon were more to my liking. But I’ve never been one to leave well enough alone, so I wanted to see what it would be like to combine a Split Toning panel adjustment on top of the Graduated Filter adjustments. Figure 4.42 shows the separate warm and cool hues and saturations applied and the Split Toning Highlights and Shadows color pickers.
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HIGHLIGHTS WARM COLOR APPLIED
SHADOWS COOL COLOR APPLIED
Figure 4.42. The Split Toning settings applied individually.
I’ll admit that adding Split Toning on top of the Graduated Filters may be just a tiny bit over the top, but nobody has ever accused me of being subtle. Figure 4.43 shows the results. You decide what you think, but I like it!
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Figure 4.43. Final post-sunset glow using both Graduated Filters and Split Toning.
HSL color correction
As a general rule, I don’t recommend walking up to a wild American buffalo to photograph it. Although I shot this image with a 24mm lens, I didn’t actually walk up to the buffalo (I’m not that stupid). Instead, I sat down on the ground when it was much farther away and waited for it to come to me. Of course, once I was done photographing the buffalo, the situation was a bit dicey ... I slowly walked away and quickly got on my motorcycle and beat feet out of there. Truth be told, I doubt the buffalo was paying any attention to me—it was chowing down, and buffalo are pretty used to people in Yellowstone National Park. Figure 4.44 shows the image before color correcting.
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Figure 4.44. An American buffalo in Yellowstone before color correction.
The primary color corrections I wanted to accomplish were to change the Hue of the green grass; punch up the Saturation of the oranges, yellows, and greens; reduce the blue-sky Saturation; and adjust the Luminance value of some of the colors. Figure 4.45 shows the three sub-panels I used in the HSL/Color/B&W panel.
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HUE SUB-PANEL
SATURATION SUB-PANEL
LUMINANCE SUB-PANEL
Figure 4.45. The HSL color adjustments with the slider adjustments.
In the Hue sub-panel, I wanted to move green from more yellow to less yellow. I moved green toward a more green color and moved yellow a bit more toward green. In the Saturation sub-panel, I wanted to punch up the color of the buffalo (orange), as well as yellow and green, but I wanted to desaturate the blue. In the Luminance sub-panel, I lightened the orange and green while slightly darkening the yellow and more strongly darkening the blue. The new result would be to have the green of the grass greener, the yellows more colorful, the buffalo more saturated and lighter, and the sky reduced in saturation and luminance.
Figure 4.46 shows the final result of the HSL color correction. Oh, if you’re curious, I didn’t use any Vibrance in this image (although I did add some Clarity).
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Figure 4.46. An American buffalo in Yellowstone after color correction.
Lens colorcast correction
The lens you shoot with can cause a lens colorcast that can be very difficult to correct in Lightroom. When the light passing through the lens strikes the sensor at a more oblique angle, you can get uneven colorcasts generally of a green or magenta color. A single WB adjustment will fail to correct this problem. If you balance for the green, the neutral becomes magenta. If you correct the magenta, the cast becomes green. Then there are uneven light falloffs. If you’re using a tilt/shift lens even on a DSLR, you may encounter asymmetrical lens falloff (vignetting) that, when combined with the colorcast, can become an even more difficult problem to address because the lens corrections can’t deal with asymmetrical lens falloff.
To really fix this problem, you need to shoot a sample image as a calibration image with the lens in the exact position regarding tilt/shift, f-stop, and focus distance of your normal shot. Use the calibration image as a basis to correct for colorcast and falloff. To shoot this, place a diffuser disk (often translucent Plexiglas) over the lens and shoot essentially just the colorcast and falloff caused by the lens.
Up to now, you couldn’t do this in Lightroom—even though the DNG specification allows for making the corrections. So, even though the DNG can do it, there was no way of selecting the calibration image, extracting the colorcast and falloff data, and applying it to other images in Lightroom. That’s about to change. Starting in late 2012, Adobe will be releasing a DNG Flat Field plug-in for Lightroom. The plug-in will be provided as a free download from the DNG product page (www.adobe.com/dng). As of this writing, I’m using a beta version of the plug-in, so it’s subject to change when the release is final. Figure 4.47 shows an image shot with the Phase One IQ 180 camera back on a Sinar 4x5 camera with a 120mm lens with a forward standard tilt to alter the focus plane and a front standard shift up for composition. The colorcast and light falloff aren’t terrible, but they’re noticeable at the top of this high key shot (which is why I shot it).
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Figure 4.47. Image before flat field corrections.
The plug-in can identify a calibration image, calculate the required corrections, and apply the corrections to real images. The only catch: you must convert the raw files to DNG before using the plug-in. You can convert raw images to DNG directly in Lightroom by choosing Convert Photo to DNG from the Library menu. Figure 4.48 shows the steps for applying the corrections.
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STEP 1: IN THE LIGHTROOM LIBRARY, SELECT THE IMAGE AND THE COLORCAST CALIBRATION IMAGE.
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STEP 2: IN THE LIBRARY MODULE, UNDER THE LIBRARY MENU, SELECT PLUG-IN EXTRAS AND THEN APPLY INTERLEAVED CORRECTION.
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STEP 3: WHEN THE DIALOG BOX APPEARS, SELECT YOUR CORRECTION OPTION.
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STEP 4: THE PLUG-IN RUNS AND CREATES A NEW DNG FILE STACKED WITH THE ORIGINAL WITH THE CORRECTIONS APPLIED.
Figure 4.48. Steps to correct colorcast and light falloff using the DNG Flat-Field plug-in.
Under the DNG Flat Field plug-in menu, there are two options: Apply interleaved correction and Apply external correction. I used the interleaved option because both the main image and the colorcast calibration image were interleaved in the same folder—as would happen when shooting in the field or studio. If you have a fixed shooting setup (as you might have for shooting copy shots of artwork), you may prefer to store your colorcast sample image in a different location. Note that the calibration image must use the exact same lens, f-stop, focus distance, and lighting as the images you want to correct. If you choose the external option, you’ll be given a dialog box to navigate to and select the external sample.
When shooting the colorcast calibration images, it doesn’t matter whether you shoot them before or after the real image. The plug-in is capable of finding the calibration image or images if you have multiple shots and calibration images. Shooting in the field with a tech camera, you may end up with a variety of different shots—just be sure you shoot a calibration image before making any lens changes. The plug-in is capable of determining which calibration images are intended for which real images. If you’re doing an exposure bracket for HDR blending, odds are, you won’t be changing your f-stop, so a single calibration image would work for all captures in a bracket. The same is true for shooting a panoramic series—as long as you don’t change the lens settings, a single calibration image will suffice.
The DNG Flat Field plug-in works only in Lightroom. You can’t use Camera Raw to select calibration images (although Camera Raw can process a DNG with the corrections already embedded in the DNG). Figure 4.49 shows the final image after the colorcast and falloff corrections have been applied. You’ll note the removal of the green colorcast and light falloff from the top of the image.
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Figure 4.49. The result of removing the colorcast and light falloff from the image.