On Fri, 2005-08-05 at 08:11 +0800, Jon Davison wrote: > Hi Rod. You must convert your RGB images to CMYK in Photoshop. 'Image - > Mode - CMYK'. > Then go; 'Image - Adjustments - Selective Colour' to bring back some of > the colours that have > changed. CMYK will increase the file size as well. > > This is because images seen on computer monitors and TV screens using > RGB have a far greater range, or gamut of colours that ink on paper > can ever have.
My understanding is that that's not necessarily true. Some truly awe-inspiring results can be achieved by things like die-sub printers, or high-res hexachrome printing on gloss stock. The issue is that there are parts of both the CMYK (and most other print colour format) and RGB gamuts that /do not overlap/. The diagram on this page might help: http://dx.sheridan.com/advisor/cmyk_color.html Thus, there are some RGB colors that can not be represented in CMYK - and vice versa. Since we usually design in RGB, it's the RGB ones that can't be represented in CMYK that generally bother people. Accurate monitor AND PRINTER profiles, plus tools that understand ICC and can provide out-of-gamut warnings will help a lot in avoiding unexpected problems when going to print. Remember that the gamut of your specific printer might well be different to that of the CMYK colourspace, too - that's part of the reason why accurate output profiles are crucial. > So Photoshop or another image editor is what you must use. Also make > sure you have 'bleed' > around your image if it is going to be trimmed. Your printer specifications will provide the required information for this. -- Craig Ringer
