Adobe illustrator 10 Manuale Utente

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Producing Consistent Color 
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Producing Consistent Color
Why colors sometimes don’t match
No device in a publishing system is capable of reproducing the full range of colors 
viewable to the human eye. Each device operates within a specific color space which can 
produce a certain range, or gamut, of colors.
The RGB (red, green, blue) and CMYK (cyan, magenta, yellow, and black) color models 
represent two main categories of color spaces. The gamuts of the RGB and CMYK spaces 
are very different; while the RGB gamut is generally larger (that is, capable of representing 
more colors) than CMYK, some CMYK colors still fall outside the RGB gamut (see 
 for an illustration). In addition, different devices produce slightly 
different gamuts within the same color model. For example, a variety of RGB spaces can 
exist among scanners and monitors, and a variety of CMYK spaces can exist among 
printing presses.
Because of these varying color spaces, colors can shift in appearance as you transfer 
documents between different devices. Color variations can result from different image 
sources (scanners and software produce art using different color spaces), differences in 
brands of computer monitors, differences in the way software applications define color, 
differences in print media (newsprint paper reproduces a smaller gamut than magazine-
quality paper), and other natural variations, such as manufacturing differences in monitors 
or monitor age.
About color management
Because color-matching problems result from various devices and software using 
different color spaces, one solution is to have a system that interprets and translates color 
accurately between devices. A color management system (CMS) compares the color space 
in which a color was created to the color space in which the same color will be output, and 
makes the necessary adjustments to represent the color as consistently as possible among 
different devices.
The following components are integral to a color-managed workflow:
Device-independent color space To successfully compare different device gamuts and 
make adjustments, a color management system must use a reference color space—an 
objective way of defining color. Most CMSs use the internal CIE (Commission Interna-
tionale d’Eclairage) LAB color model, which exists independently of any device and is large 
enough to reproduce any color visible to the human eye. For this reason, CIE LAB is 
considered device-independent.