Editing Subtractive color (section)

== CMY and CMYK color models and printing processes ==
{{Main|CMY color model|CMYK color model}}
[[File:CMY.jpg|Cyan, magenta and yellow color filters|thumb]]

In [[color printing]], the usual primary colors are [[cyan]], [[magenta]] and [[yellow]] (CMY). Cyan is the complement of red, meaning that the cyan serves as a filter that absorbs red. The amount of cyan ink applied to a white sheet of paper controls how much of the red light in white light will be reflected back from the paper. Ideally, the cyan ink is completely transparent to green and blue light and has no effect on those parts of the [[visible spectrum|spectrum]]. Magenta is the complement of [[green]], and yellow the complement of [[blue]]. Combinations of different amounts of the three inks can produce a wide range of colors with good [[saturation (color theory)|saturation]].

In [[inkjet printing|inkjet color printing]] and typical [[mass production]] [[lithography|photomechanical printing processes]], a black ink K (Key) component is included, resulting in the [[CMYK color model]]. The black ink serves to cover unwanted tints in dark areas of the printed image, which result from the imperfect transparency of commercially practical CMY inks; to improve image sharpness, which tends to be degraded by imperfect registration of the three color elements; and to reduce or eliminate consumption of the more expensive color inks where only black or gray is required.

Purely [[color photography|photographic color processes]] almost never include a K component, because in all common processes the CMY dyes used are much more perfectly transparent, there are no registration errors to camouflage, and substituting a black dye for a saturated CMY combination, a trivial prospective cost-benefit at best, is technologically impractical in non-electronic [[analog photography]].