Universal Principles of Color

22CMYK

The standard cyan, magenta, yellow, and black inks used in four-color process printing

Printing inks are based on the optimal subtractive primaries of cyan (C), magenta (M), and yellow (Y), with black (K) added to create a four-ink system. The black ink is referred to as K because it is the key color used to add detail to an image.

There are several practical reasons why CMYK is preferred to CMY. First, it is difficult to get a pure black by mixing cyan, magenta, and yellow inks. Second, if dark colors are produced by mixing CMY, the amount of ink laid down is substantial and can cause the paper to ripple. Third, black ink is less expensive ...