This blog hasn’t been updated since sometime last September. What I’ve been doing in the meantime is writing a book which is now complete and under review at a publishing house. It’s 45,800 words long, with over 240 illustrative photos. The title is “Explorations in Photography,” and its purpose is to help advanced amateur photographers improve their artistic skills.
Finishing and editing was a big undertaking, and now that it’s done, I can get back to taking, editing, and restoring photographs – and writing about all of that good stuff.
Only recently pixel-peeper-and-nit-picker-in-chief Ken Brown called me up to not to suggest I check out a certain book, but to order me to buy a copy forthwith!
As usual, Ken was right.
It turns out that hidden in Photoshop, lurking in some of the disagreeably complex functions, such as “Mode,” is Lab Color (more properly CIELAB or L*a*b) color.
I am not a LAB guru. I’m an experimenter and dilettante, for the moment at least. THE guru of LAB is Dan Margulis, whose book on the subject is lively but intense. It’s available through Amazon, and the full title is Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Color Space. Just search for Canyon Conundrum and you’ve got it.
LAB color actually has nothing much to do with laboratories. It stands for Luminance Channel, A channel, and B channel. Luminance handles all the light-to-dark information in an image. The A channel handles green and magenta, while B balances Yellow and Blue.
What makes this scheme special is that in RGB color, which we (and our cameras) use every day, when you adjust color, you adjust exposure as well, whether or not you want to. That’s why RGB workflows encourage you to make your color corrections first, then adjust exposure and all the rest afterwards.
In LAB color space, there is no connection between color and luminance, at least technically speaking. You can set your colors, then adjust your L values, just as in RGB space, BUT there are two main differences: what you do to color doesn’t affect luminance (and vice-versa). And you cannot alter red (magenta) without affecting green, and you can’t change yellow without affecting blue.
This is confusing. Yup. Sure is. But practically speaking, LAB offers you opportunities RGB, with its linkage between luminance and color, can’t provide.
1. LAB works best on underexposed images with lousy contrast. You can fix the color, THEN mess with the contrast (luminance values) using a Curves Adjustment Layer. When you’re in LAB color, you make adjustments using a curves adjustment layer is. When you create the curves layer, Photoshop automatically sets it up with L, a, and b channels. Each has sliders and a graph, and in later versions of Photoshop, a light gray histogram which makes life very easy.
2. You can achieve much more “natural” or “realistic” color than you can in rgb. Green grass can be made to look realistic, as can leaves: both are a real problem in rgb color space. “Misty Pond” gives a good example of this ability.
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| Misty Pond, as edited in RGB |
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| Misty Pond Edited in LAB for a more natural color |
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| Matanuska Glacier detail, as shot |
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| Matanuska detail edited in LAB |
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| Screen shots showing RGB editing, left, and LAB editing, right. The right-hand version is probablyunobtainable in RGB. You have to edit in LAB, then convert back to RGB. |
3. You can “bump up” color without touching luminance; this means that effectively you can increase contrast without losing details in deep shadows or highlights.
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| Glacial Grooves, best RGB |
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| Glacial Grooves, LAB. Note how contrast has improved |
4. For advanced users, you can do a wonderful job on skin tones.
The essential things to remember about LAB space are two, and they are hard to get your head around.
First, in LAB space, luminance has nothing to do with color.
Second, in LAB space, any change to magenta affects green, and any change to yellow affects blue. And vice versa. Of course, the a and b channels react together to crate the color for your image.
Both freedom and madness this way lie. In the words of the song, “You can’t have one without the other” – for color. But you CAN have one without the other for light as separate from color! My advice: go experimenting.
The madness part is that it’s possible to do some very funky things with color … and it’s hard to learn to deal with a color space in which a 1 % change in either a or b channel can significantly change you image. Gently, gently is the word.
LAB works best, as I said, for handling flat and monochromatic images. Images with vibrant color may already be just peachy in RGB. But in my experience LAB allows you to create a greater sense of depth without sacrificing details, and it can just plain blow you away.
I’m including a handful of examples. Some show the best I could do in RGB, then in LAB color. Others show the “as shot” version and the LAB corrections. Put on your fantasy caps for some of these!
Finally, for readers who have stuck with me this far, I’ve constructed a couple of simple “get you started” Photoshop actions to automate basic steps for you. You can get this action for free, just for asking. I'll email it to you. The first action pops you into LAB space, intensifies existing colors by 10% without touching the L channel. The action leaves you at the L channel, ready to play with lightness and contrast. The second action adds a small amount of sharpening to the L channel only, then puts you back into RGB space, ready for further editing. You can download the action HERE
Obviously, these are just to get you started. Life in the LAB can be a rich, fast, and intriguing place to live!
