In the subtractive color model, magenta, yellow, cyan, and black are the primary colors. They are also called CMYK, with K standing for black because the letter B is already taken by RGB. Mixing cyan, yellow, and magenta together creates a dark muddy brown, so this is why black has been added as the fourth primary color, to get clean blacks. You subtract to get white. To get a lighter color use less of each color, or to get a darker color use more of each color. Subtractive is the color model used for working with pigments, as in painting and color printing. In RT3D, the subtractive color model governs how colors are blended together, like with transparency and texture blending. See also additive color model.

This definition is in context to Real Time 3D. See more contextual defintions for Subtractive Color Model.