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The properties of color
Hue, saturation, and brightness
A color can be described in terms of three varying characteristics:
• Hue—tint (the qualitative aspect of a color—red, green, or orange)
• Saturation—the purity of the color
• Brightness—relative position between white and black.
While the CIE chromaticity diagram (plate 2) conveys hue and saturation, a three-
dimensional color model is required to add the brightness component (plate 3).
Many computer applications include dialog boxes in which you choose colors by
manipulating hue, saturation, and brightness. For example, Photoshop uses a square
Color Picker (plate 4) which can be reconfigured according to your preference.
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
DocuColor 40 CP 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
(plate 5). 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 (plate 6).
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.
