Color Management in Adobe Photoshop
Some inkjet, toner-based, photographic, and other non-PostScript printers print in RGB mode, meaning the RIP or driver is designed to accept RGB rather than CMYK data. This document explains how work effectively in Photoshop CS4 using RGB data even if the printer prints with CMY, CMYK, CMYKcm (light cyan and light magenta), or some other combination of inks.
RGB Printer Profiles: Adobe Photoshop CS3/CS4 (Download PDF: 2.4MB)
Creative Suite 6 ICC Color Settings (Download PDF: 3.2MB)