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Additive and
subtractive
color systems
Color devices used in desktop publishing and printing simulate the range of
visible colors using a set of primary colors that are combined to create other
colors. There are two methods of creating a range of colors from a set of
primary colors. Computer monitors and scanners use the additive color
model. Printing technologies, including KX-P8420 print devices and offset
presses, use the subtractive color model.
Additive (RGB) color
Color devices that use the additive color model make a range of colors by
combining varying amounts of red, green, and blue light. These colors are
called the additive primaries. White is created by adding the maximum
amount of red, green, and blue light available. Black occurs wherever all
three colors are absent. Grays are created by adding varying amounts of all
three colors together. Combining varying amounts of any two of the additive
primaries creates a third, saturated hue.
A familiar device that uses this color model is the computer monitor.
Monitors have red, green, and blue phosphors that emit varying amounts
of light to display a given color. Scanners create digital representations of
colors by measuring their red, green, and blue components through colored
filters.
Subtractive (CMY and CMYK) color
The subtractive color model is used in color printing, and in 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 uses 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 question.
The subtractive primaries are cyan, magenta, and yellow; they absorb
red, green, and blue light, respectively. 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, 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.
Working with Color
55
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