CMYKi stands for "Cyan Magenta Yellow Black" describing the four basici colors used for printing color images. CMYK colors are "subtractive" meaning the colours darken as you blend them. Though technically it would follow that equal amounts of pure cyan, magenta, and yellow should produce black when blended, due to the impurities present in inks a true black is difficult to create. For this reason black (K) ink is typically included with the three other colors. The letter "K" is used to avoid confusion with blue in RGBi.
CMYK
