Color printing yellow (minus-blue) overprinted by magenta (minus green) yields red. Where all three inks may overlap, almost all incident light is absorbed or subtracted, yielding near black, but in practical terms it is better and cheaper to use a separate black ink instead of combining three colored inks. The secondary or subtractive colors cyan, magenta and yellow may be considered "primary" by printers and watercolorists (whose basic inks and paints are transparent). Two graphic techniques are required to prepare images for four-color printing. In the "pre-press" stage, original images are translated into forms that can be used on a printing press,
Secondary color secondary CMY colors (with secondary colors in boldface) are: Ideally, combining three perfect primary colors in equal amounts would produce black, but this is impossible to achieve in practice. Therefore a "key" pigment, usually black, is added to printing to produce dark shades more efficiently. This combination is referred to as CMYK, where K stands for Key. Before the discovery of CMY, at least as far back as Goethe, the best primary colors were thought to be red, yellow, and blue. Mixing these pigments in equal amounts produces orange, green, and purple: That is, the primary and secondary RYB colors