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22.1 Key Concepts
To use color management effectively, you should understand the following key concept:
• Color in PlanetPress Design (Page 340)
22.1.1 Color in PlanetPress Design
How can I create the closest possible match between the colors I see on-screen in PlanetPress Design and the
colors that print?
This topic contains the following information to help you create a close match between on-screen colors in
PlanetPress Design and printed colors:
• The Challenge in Matching Color (Page 340)
• Color Management Systems (Page 341)
• Color Management in PlanetPress Design (Page 341)
• Color Spaces (Page 342)
The Challenge in Matching Color
There are three major difficulties in matching color: the difference with color created with light and color
created with pigment, the representation and control of color in physical devices, and our perception of color.
1. Light vs. pigment
The monitor produces the color you see on-screen with light while the printer produces color with
pigment. The set of colors, or gamut, you can produce with light is not identical to the set you can
produce with pigment. Thus there are colors you can produce on a monitor and not on a printer, and
vice-versa.
The monitor uses three primary colors of light (red, green, blue) to produce all the colors you see on-
screen. It mixes different amounts of each of the primaries to produce a particular color. An on-screen
color is specified as three numeric values, the first describing the amount of red, the second the amount
of green, and the third the amount of blue light to use to create the color. Thus these are often referred
to as RGB (Red Blue Green) colors.
The printer uses three primary colors of ink (cyan, magenta, yellow) and black to produce all the colors
it prints.
The set of colors you can produce with light (the RGB gamut) is larger than the set of colors you can
produce with pigment (the CMYK gamut). Thus monitors can produce more colors than printers.There is
a significant overlap between the two gamuts however, and, in those cases, the problem becomes how
to match a color that it is possible to create with either light or pigment, on different physical devices.
2. Representation and control of color in physical devices
The difficulty with physical devices is that none are stable enough to ensure a consistent representation
of a given color. Physical devices for our purposes are monitors and printers.
Monitors The same color can vary across monitors due to factors such as the phosphor specification,
the calibration, and the age of the individual monitor. Even on the same monitor the color can change as
the monitor ages or loses its calibration. The set of colors a monitor can display (its gamut) can also
vary across monitors.
Printers The same color can also vary across printers or on the same printer due to factors such as the
inks a printer uses, the amount of ink in the printer at the time you print, and the physical properties of
the paper on which you print.
3. Color perception
Our perception of a color can change with variations in the ambient lighting. A color that appears very
rich under subdued lighting may appear washed out under bright lighting. Our perception of a color can
also change due to the colors that appear alongside it. The same color on two different backgrounds can
appear to be two different colors. Finally, two individuals may not see the same color.
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