Why do some output devices prefer CMYK?
While most inkjet printers will use either Cyan, Magenta, Yellow and Black (or even an additional two colors to extend the gamut), most printers prefer an RGB file for output. One reason is that RGB by nature usually has a wider color gamut. The other reason is that most such desktop printers are driven by QuickDraw (Mac) or GDI print drivers and these drivers do not support CMYK files. If CMYK files are sent to such a printer driver, an unknown (and usually quite poor) CMYK to RGB conversion will take place since these drivers require RGB files only. So when one simply wants the best looking output from an inkjet printer, send RGB data, ideally an RGB file that has been optimized for this printer using an ICC profile. If a user wishes to send CMYK data to an inkjet, the only logical reason would be to simulate another CMYK device on this inkjet. A CMYK file may be destined for a Contract Proof, such as a 3M Matchprint which the user wants to first simulate this based on their own inkj
