This year, we're getting "clubcard":http://clubcard.ca to print our annual calendars. However, living in the world of reflected light they accept artwork in "CMYK":http://en.wikipedia.org/wiki/CMYK colour space, and not "RGB":http://en.wikipedia.org/wiki/SRGB . This opened up the can of worms that we had mostly been ignorant of before -- colour management. There are lots of resources on the web for how to set up a workflow for colour management. However, I needed to stitch a pages from different sRGB sources, and convert them to CMYK. The best way I found to do this was: * rasterize the images to "TIFF":http://en.wikipedia.org/wiki/Tagged_Image_File_Format in RGB space. I used "ghostscript":http://www.cs.wisc.edu/~ghost/ * get sRGB and CMYK colour profiles from "Adobe":http://www.adobe.com/support/downloads/detail.jsp?ftpID=2957 * use "LCMS":http://www.littlecms.com/ (Little Color Management System) to project the images from RGB to CMYK * compress the resultant tiffs and hand them off Although ghostscript can rasterize directly to CMYK TIFFs, I was unable to find how to apply a colour profile to the process, and the results were poor. In the future, I'll just use "Scrubus":http://www.scribus.net/ to generate the whole thing directly in CMYK.