The Hidden Power of Photoshop CS: Chapter 2: Color Separations. Pt. 1. By Sybex - WebReference.com-:
"Photoshop provides many tools that seem to produce some magic behind the scenes. Channels, one of the most prominent of these tools, allow you to work directly with components of a color model, such as RGB or CMYK. But, as we saw in the previous chapter, channels can actually be simulated using some simple light theory. Understanding what the channels represent can help you make more intelligent color and correction decisions, and can very much change the way you work with images.… "

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