Ricoh AP3850C Service Manual download pdf (Page 168)

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 (color example 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 printer toner 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.

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Ricoh AP3850C Service Manual Page 168