Desktop Colour Separation (DCS) is an enhanced Encapsulated PostScript file format that was introduced by Quark, Inc.[1] It is now primarily used for specialised graphics work particularly images that use multiple channels, e.g. when applying different spot colours to each part of a greyscale image.[2]
In DCS a CMYK graphic is separated into five files; a main file and four pre-separation files, one for each CMYK process colour. The main file contains an indication of which separation files are needed and where to find them, together with a composite image information which is used to print a composite of the image.[3]
When output to a PostScript printer, the printer driver reads the information in the main file and assigns the cyan, magenta, yellow, and black files to their corresponding separation files.