[Award Winner] Bitmapped Images - The technical side of things explained.

[Redrobes]

These letters stand for Cyan, Magenta, Yellow, and Black (not to confuse B with blue I suppose). The first three of these being the primary colors for paint or color absorbing materials and are opposite to RGB which are the primary colors for light or color emitting materials. If you take a full light spectrum and remove red from it then it looks cyan in color. If you remove green then it looks magenta and if you remove blue then it looks yellow. Similarly if you paint some magenta and yellow then it looks red, you can paint cyan and yellow then it looks green and cyan and magenta looks blue. If you paint perfect cyan, magenta and yellow all together then its goes black. However the inks used in printers are not perfect and it comes out a dark muddy brown color and people like their black very black so the addition of the last K channel accounts for that.

As mentioned before there is not a single equation to convert from RGB to CMYK and some color curves are usually used to look up what levels of CMYK should be used for any RGB. The usual rough rule is work out how much gray is involved and get that on the K channel and work out the remainder with the C,M and Y. Because of the funny color curves used and four axis color space then averaging colors in CMYK can also produce odd shades when blending colors.