LAB Color and Tonal Adjustments in Photoshop
Adapted from Creative Landscapes: Digital Photography Tips & Techniques (Wiley Publishing)
By Harold Davis
A color space, or color model, is a structure for referencing and notating color values. As you likely know, the RGB color space is a color space with three channels—Red, Green, and Blue—commonly used in LCDs and monitors. CMYK is a four-channel color space—the color channels are Cyan, Magenta, Yellow, and Black—used to describe the color values in images that will be printed in books and magazines.
LAB is a three-channel color model—I’ll explain how the channels work in a moment. Unlike RGB and CMYK, LAB is a theoretical model in the sense that you can’t save a LAB image as a JPEG for display on the web, and there are no reproduction processes that use LAB to print things. But LAB has a couple of features that make it excellent for manipulating colors. Once you get the hang of it, it is easy to use LAB colors to make your landscapes go from drab to fab!
In Photoshop, to work in LAB you have to convert your image into the LAB color space. Once you are finished working in LAB, if you want to actually do anything with your photo, you need to convert it back to RGB or CMYK.
The two features that make LAB particularly powerful for working with color are that it separates grayscale information completely from color information, and that each of the color channels are color opponent, meaning they include information both about a color and its opposite color. The ways these features work in Photoshop are shown in the figure below.
You have to work with LAB for a while to understand just how much these facets of LAB can be used to improve your landscape photos; a good example is the next case in which I’ll show you how to use these LAB features to make the colors of a rainbow bolder and brighter.
LAB Color and Tonal Adjustments
I’ve told you that LAB is fabulous for working on color, now let’s take a look at how you can use it practically.
The diffuse mist under Yosemite Falls (shown below) lent itself to a rainbow when the sun peeked through the clouds. But looking at the image on my computer, I was surprised by how dull the colors were. This would not do!
Converting to LAB color
Increasing Contrast with LAB
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Adapted with permission from Creative Landscapes: Digital Photography Tips & Techniques by Harold Davis . Copyright © 2011 Wiley Publishing