4. Color Essentials: What Makes a Color
You may have been taught back in kindergarten that the primary colors are red, yellow, and blue, and that all other colors can be made from them. Bruce still vividly recalls the day when his first-grade teacher, Mrs. Anderson, told him that he could make gray by using equal amounts of red, yellow, and blue. After looking at the lurid, weird, multicolored mess that was supposed to be a gray cat, he quite sensibly started over using a 2B pencil, and concluded that Mrs. Anderson was either color-blind or clueless. He traces his sometimes-inconvenient tendency to question authority to that day.
The details of Mrs. Anderson's lesson were certainly fallacious, but they contained an important kernel of truththe notion that we can create all colors by combining three primary constituents. People have many different ways of thinking about, talking about, and working with color, but the notion of three ingredients that make up a color occurs again and again. Art directors may feel comfortable specifying color changes with the terms hue, lightness, and saturation. Those who came to color through the computer may be more at home with levels of RGB. Scientists think about color in all sorts of strange ways, including CIE Lab, HSB, and LCH. And dyed-in-the-wool prepress folks think in CMYK dot percentages.
Although Photoshop tries to accommodate all these ways of thinking about colorand it does a pretty good jobmany Photoshop users find themselves locked into seeing color in only one way. This is natural and understandablewe all have one way of thinking about color that seems more sensible than the othersbut it can make life with Photoshop more difficult than it needs to be. If you understand that all the different ways of looking at color are based on the same notioncombining three ingredientsyou can learn to translate among the ways Photoshop lets you work with them, and choose the right one for the task at hand.
"Wait a minute," you say. "CMYK has four constituents, not three!" You question authority too, when that authority doesn't make sense. Well, in our role as temporary authority figures, we'll do what authority figures often do when asked hard questions: We ask you to trust us. Set this issue aside for the moment. We promise we'll deal with it later.
In this chapter, we take a hard look at some fundamental color relationships and how Photoshop presents them. This stuff might seem a little theoretical at times, but we urge you to slog through it; it's essential for our later discussions about tonal and color correction.