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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 
for creating a range of colors from a set of primary colors. Computer monitors and scanners 
are based on the 

. Printing technologies, including the Color Server and 

offset presses, are based on the 

.

Color devices that use the additive color model create a range of colors by combining varying 
amounts of red, green, and blue light. These colors are called the 

 

(illustrated in the following figure). 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 equal amounts of all three color together. Combining varying amounts of 
any two of the additive primaries creates a third, saturated hue.

A familiar device that is based on this color model is the computer monitor, illustrated in the 
following figure. Monitors have red, green, and blue 

 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.

The subtractive color model is the basis for color printing, 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 starts with a “white” or neutral 
light source containing light of many wavelengths. Inks, toners, or other 

 are used to 

selectively absorb (subtract) certain wavelengths of light that otherwise would be reflected or 
transmitted by the media in use. 

 are cyan, magenta, and yellow; they absorb red, green, and blue 

light, respectively (as illustrated in the following figure). 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. In theory, combining all three subtractive primaries 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. Consequently, color printing uses four 

yan, 

agenta, 

ellow, and blac

 (

). The use of black toner produces 

rich, solid blacks and allows for improved rendering of black text.

Different color reproduction techniques have different color capabilities, or 

transparency films have comparatively large gamuts, as do color monitors. The color gamut 
that can be produced using process inks or 

 toners 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 Color Server, nor can they be reproduced on a press 
using 

. Moreover, different printers have different gamuts. Some colors your 

printer can produce cannot be reproduced on an offset press, and vice versa. The following 
figure illustrates this concept of differing gamuts.

You must account for the gamut of your printer when designing on a color monitor. When 
printed, colors that fall outside the printer gamut are “mapped” to printable colors. This 
process, referred to as 

, takes place when color data is converted or adjusted 

to meet the gamut requirements of a printer. 

The Color Server is specially designed to perform gamut mapping at high speed with 
high-quality results. It provides these color management features automatically, using either 
built-in default settings or settings you select for a particular print job. For added flexibility, 
you can also use the Color Server color management system in combination with the color 
management systems on Windows and Mac OS computers.