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Chapter 11 ∣ Color
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visually rather than physically. Varying combinations
of tiny, closely spaced dots of cyan, magenta,
and yellow ink absorb and reflect the different
wavelengths of light to produce different colors.
The two color formations act almost as
opposites. On our color wheel, the additive colors
are the result of mixing the subtractive colors
together. While the combination of all three additive
colors equals white, the combination of the three
subtractive colors equals black. See Figure 11-22.
Because inks are not as pure as light, the black
is muddy and would require a heavier ink deposit
on the paper, resulting in an increased drying time.
Adding black as the fourth color is not only more
cost-effective since it is less expensive than color
inks, it also enhances imagery on press. Black
allows greater and crisper detail, and deeper,
more well-defined shadow areas in imagery. In
the descriptions of the subtractive color system,
black is designated with the letter K. Thus, the four
process colors are described in abbreviated form
as CMYK.
Color Separation
Color separation is the process of dividing
the colors of a multicolored original into the
subtractive, or printing, primaries (CMY) and
black (K). The CMYK color separations are used
to prepare printing plates, Figure 11-23. For
years, color separations were created using three
different methods: direct screen photographic,
indirect screen photographic, and electronic.
Image manipulation, page geometry, and
drawing software either show or create the
separations automatically. In Adobe® Photoshop®,
the separations are shown in the Channels panel.
Each file will show the separations based on
the color space of the image. Using the color
separations panel under the output window in page
layout software, each file shows the separations
or plates necessary to reproduce the document.
By clicking on the eye next to the separation, the
individual colors can be turned off or on to show
custom views and ensure that the proper data is
on the proper color. See Figure 11-24.
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Figure 11-22. Additive color formation. Red, green, and blue
additive primaries can be mixed in pairs to form magenta,
yellow, and cyan. Mixing all three results in white light.
M C
Y
Subtractive Colors
B
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Figure 11-23. The Separations Preview panel in a page
layout application shows the number of colors in the
document needed to print.
G R
B
Additive Colors
A