White light is a mixture of all the colors of light; however, only three primary colors are actually needed to make white light. These three primary colors are red, green, and blue. Not only do these three light primaries produce white light, but they produce any and all other colors; for example, imagine a blue, a green, and a red spotlight shining on a white screen so the spotlight circles partly overlap. There are three places where two of the light primaries overlap and one place where all three light primaries overlap. In the areas where two primaries overlap, a distinctly new color is created

Figure 12-1. Mixed beams of the three primary colors of light.

(fig. 12-1). When you overlap red and green, yellow is created; green and blue, cyan is created; blue and red, magenta is created. In the area where all three light primaries overlap, you, of course, have white.

In the actual production of color prints, you should remember that yellow is greenish red; cyan is greenish blue; and magenta is bluish red.

The above information should help you remember the colors of light that make up yellow, cyan, and magenta, which are the light secondaries. Light secondaries are the colors produced when two light primaries are mixed.

Additive Primaries

Now that you have an understanding of light primaries, they will be called the additive primaries. The name additive primaries indicates that certain colors of light can be added together to create distinctly new colors.

As explained in chapter 2, color films and papers have three separate emulsion layers that are sensitive to red, green, and blue light. Because the emulsions are sensitive to the additive primaries, they can record all colors. In the three emulsion layers, three separate, superimposed images are formed and when viewed together, they give a full range of colors.

The color formation, however, is not direct; for example, in a color print, a cyan image is formed in the top or red sensitive emulsion layer, a magenta image in the middle or green sensitive layer, and a yellow image in the bottom or blue sensitive layer. These three colors or dyes-cyan, magenta, and yellow-are what produce the colors we see when we view a color print. These colors-cyan, magenta, and yellow-are called the subtractive primaries.