Xerox Phaser 7750 User Guide

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PhaserMatch and PhaserCal 4.0 User Guide
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Color management is based on color spaces. The range of colors, or gamut, perceived by the 
human eye, captured on film, displayed on a computer monitor, and rendered by a printer vary 
significantly. Each has its own color space, a mathematical means of describing its colors. 
RGB is an additive color space that combines red, green, and blue light to create all other 
colors. Monitors, digital cameras, and scanners typically use RGB colors. CMYK color, on the 
other hand, is a subtractive color space using cyan, magenta, yellow, and black inks on paper to 
absorb red, green, and blue light. The remaining reflected light is the color perceived by the 
viewer.
Both RGB and CMYK color are device dependent color spaces; the colors they render depend 
on the device that produces the colors. Additionally, converting an image from RGB to CMYK 
compresses the colors into a smaller gamut. To complicate matters more, the CMYK color 
space of one printer can vary significantly from the CMYK color space of another printer. As 
the graphic below shows, the colors reproducible by different mediums can vary significantly.
The publishing industry has settled on a system of color management developed by the 
International Color Consortium (ICC). ICC-based color management relies on two things: 
device profiles called ICC profiles, which characterize how individual devices produce color, 
and a color engine (also called a color matching module or CMM), which reads those profiles 
and translates and corrects colors between devices.
ICC-based color management relies on a device independent color space. One of the common 
color spaces specified for use is CIE L*a*b* (CIE Lab, LAB). This color space provides a link 
between device dependent color spaces specific to various devices. LAB color space is based 
on the way the human eye perceives color and is device-independent. A LAB color engine can 
translate RGB, and CMYK values to and from LAB values. This translation acts as an 
interpreter between the color spaces. ColorSync, a color-management software for the 
Macintosh operating system, currently supports CMM color engines from vendors, such as 
Introduction to Color 
Management
1.
Color visible to the human eye
2.
Color film
3.
Color monitor
4.
Printer offset press on coated paper
5.
Offset press on newsprint