On Mon, 31 Oct 2005, James Puckett wrote:
I am writing to see if there are suggested methods for ensuring good color conversion of rendered Chimera images from RGB to CMYK in Photoshop (or other image editing programs). When printing to a Tektronix Phaser 740 color laser, I am getting poor correlation between screen colorings and the printed ones. I have heard that the CMYK color space is basically a subset of the RGB color space. If this is actually the case, is there a recommended way to pick RGB colors that are relatively "safe" for conversion to a CMYK color space?
Matching screen and print colors is getting easier. If you have Adobe PhotoShop, the best thing to do would be to read its help information on "Producing Consistent Color" and follow those recommendations. Microsoft has a website <http://www.microsoft.com/whdc/device/display/color/icmwp.mspx> about "Color Management and Windows" that discusses many of the same issues. For Apple's Mac OS X, read about its ColorSync technology, <http://www.apple.com/macosx/features/colorsync/>. All of the above color management systems use ICC color profiles (<http://www.color.org/>). The basic idea is that you need a color profile for your screen and your printer and those profiles are used to match the colors. The color gamut of a screen and a printer vary greatly -- screens are much brighter than printers, but printers can produce colors that screens can't and are good at subtle differences in dark colors. Luckily, manufacturers usually provide an ICC color profile -- but to get the best results you'll need create your own using a colorimeter (e.g., <http://www.colorvision.com>). For Windows, if you do not have a printing program that supports color profiles, you can use the free ICC Profile Conversion Software from Draw Creek Photo, <http://www.drycreekphoto.com/tools/profile_converter/>. Good luck! Greg Couch UCSF Computer Graphics Lab gregc@cgl.ucsf.edu