Photoshop Lab Color- P2: LAB has a reputation for enormous power, yet virtually all reference materials that advocate its use illustrate its capabilities with a single class of image. This chapter introduces the basic LAB correction method and explains why it is so extraordinarily effective. if you happen to have a picture of a canyon. | LAB by the Numbers 31 don t pick up as well as human observers do. Steepening the AB channels is extremely effective in bringing them out. Second canyons don t have brilliant colors the colors in Chapter 1 are far less vivid than in say Figure . It would be difficult to enhance canyon colors so much that they couldn t be reproduced accurately in CMYK or RGB. Canyons are therefore very good things to hit with AB curves. Something like Figure needs to be approached with caution. You should now be able to identify colors using LAB terminology. Check that you can by going over the Review and Exercises section which offers a quick quiz. If you pass it you can move on to Chapter 3 if you like. The remainder of this chapter goes into more detail about what happens when LAB produces the unreproduceable and more about why steepening the AB is a better way to emphasize color than attempting to do the same thing in RGB. Review and Exercises If you re working with an RGB file how would you know whether a certain object will reproduce as neutral that is white gray or black How do you know that an object will reproduce as neutral if you are working in LAB Why are the A and B channels when viewed on their own as they are in Figure never white or black but only various shades of medium gray How does the L channel viewed alone compare to a version of the file that s been converted into grayscale Which colors are denoted by positive and negative numbers in the A and B channels Refer back to Chapter 1. Match each item in the left column with its typical corresponding LAB value. Answers in box on page 33. Photoshop LAB Color The Canyon Conundrum Copyright 2006 Dan Margulis 1. The sky in Figure 2. The lake in Figure 3. The pinkish background of the Review box on page 14 4. The large magenta circles in Figure 5. The African-American skintone in Figure A. 86L8A 8 B B. 49L 4 A 10 B C. 74L13A19B D. 52L81A 7 B E. 67L 3 A 30 B 32 Chapter 2 A Closer Look I .
