Whereas RGB is used for computer and TV screens, the Yellow-Magenta-Cyan (YMC) colour model is used in colour definition for hardcopy media, such as printed pictures and photographic prints on paper. The principle of YMC colour definition is to consider each component as a coloured filter. It is based on the subtractive principle of colour.
In YMC model, the filters are yellow, magenta and cyan. Each filter subtracts one primary colour from the white: the magenta filter subtracts green, so that only red and blue are left; the cyan filter subtracts red, and the yellow filter subtracts blue. Where the magenta filter overlaps the cyan filter, both green and red are subtracted and so we see blue. In the central area, all light is filtered so the result is black. Colour printing, which uses white paper and yellow, magenta and cyan ink, is based on the subtractive colour scheme. When sunlight falls on a colour-printed document, part of it is filtered out by the ink layers and the colour remaining is reflected from the underlying paper.