Print Device Gamut - Xerox DocuColor DocuColor 4 User Manual

6.1 The properties of color
Subtractive (CMY and CMYK) color
The subtractive color model is used in color printing, and in color photo-
graphic prints and transparencies. While the additive color model simulates
the visible spectrum of color by adding light of three primary hues, the sub-
tractive color model uses a "white" or neutral light source containing light
of many wavelengths. Inks, Dry Inks, or other colorants are used to selec-
tively absorb (subtract) certain wavelengths of light that otherwise would be
reflected or transmitted by the media in question.
The subtractive primaries are cyan, magenta, and yellow; they absorb red,
green, and blue light, respectively. Combining any two subtractive prima-
ries 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. Combin-
ing all three subtractive primaries in theory yields black, but due to deficien-
cies of cyan, magenta, and yellow colorants, combining these three prima-
ries actually yields a muddy brown. Black colorant is added to compensate
for the deficiencies of cyan, magenta, and yellow colorants, and consequently
color printing uses four process colors: Cyan, Magenta, Yellow, and blacK
(CMYK). The use of black ink helps in producing rich solid blacks and also
allows for improved rendition of black text.
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6.1.5

Print device gamut

Different color reproduction techniques have different color capabilities, or
gamuts. Color transparency films have comparatively large gamuts, as do
color monitors. The color gamut that can be produced using CMYK Dry Inks
on paper is smaller. This is why some colors that can be displayed on a color
monitor, especially bright saturated colors, cannot be reproduced exactly by
your DocuColor 4 LP/CP-nor, for that matter, can they be reproduced on
press using process colors. Moreover, different print devices have different
gamuts-some colors that your print device can produce cannot be reproduced
on an offset press, and vice versa. The following illustration provides a graphi-
cal representation of this concept.
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