Canon ColorPASS-Z5000 Color Manual page 178

A
A-4 Desktop Color Primer
Subtractive (CMY and CMYK) color
The subtractive color model is the basis for color printing and for color photographic
prints and transparencies. While the additive color model simulates the visible
spectrum of color by adding light of three primary hues, the subtractive color model
starts with a "white" or neutral light source containing light of many wavelengths.
Inks, toners, or other colorants are used to selectively absorb (subtract) certain
wavelengths of light that otherwise would be reflected or transmitted by the media in
use.
The subtractive primaries are cyan, magenta, and yellow; they absorb red, green, and
blue light, respectively (plate 7). Combining any two subtractive primaries creates a
new color that is relatively pure or saturated. For example, you can make red by
combining magenta and yellow, which absorb green and blue light, respectively. White
occurs when no colorant is applied. Combining all three subtractive primaries in
theory yields black, but due to deficiencies of cyan, magenta, and yellow colorants,
combining these three primaries actually yields a muddy brown. Black colorant is
added to compensate for the deficiencies of cyan, magenta, and yellow colorants.
Consequently, color printing uses four process colors: Cyan, Magenta, Yellow, and
blacK (CMYK). The use of black toner helps in producing rich, solid blacks and allows
for improved rendering of black text.
The CMYK colorants used in offset printing and by your ColorPASS copier are to
some degree transparent. When one layer of colorant is applied on top of another, you
see the effect of both. To create a range of intermediary colors, a method is required for
varying the amount of each colorant that is applied. A technique called halftoning is
used in offset printing, while color print devices typically use a proprietary system for
applying ink or toner colors that is similar to halftoning.