Xerox Fiery color server, User Manual

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A-7 Desktop Color Primer
Subtractive (CMY and CMYK) color
The subtractive color model is the basis for color printing, 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 (as shown in the following figure). 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. In theory,
combining all three subtractive primaries 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 :
C yan, M agenta, Y ellow, and blac K ( CMYK ). The use of black toner produces rich,
solid blacks and allows for improved rendering of black text.