RGB

Also see Grey scale
There are many models of specifying colors depending on the application or equipment. Television sets and color monitors have three electron guns in them. Each gun controls one of the three primary colors (red, green and blue) thus the common term for this is RGB.

RGB (red, green blue) is one of the two prevailing color models for use in electronic publishing. It is the means through which an image is displayed on a computer screen. RGB is based on a "subtractive" color scheme, which means that it defines white as a state in which all three of the available colors are present in the maximum amounts, and black as a state in which all three colors are completely absent. In RGB mode, colors in between black and white are achieved by withholding or "subtracting" varying amounts of the three available colors.

CMYK (cyan, magenta, yellow and black) is a model used in process colors such as a printing plant (magazines, brochures etc.).

The CMYK model is based on the light-absorbing quality of ink printed on paper. As white light strikes translucent inks, part of the spectrum is absorbed and part is reflected back to your eyes.

In theory, pure cyan (C), magenta (M), and yellow (Y) pigments should combine to absorb all color and produce black. For this reason these colors are called subtractive colors. Because all printing inks contain some impurities, these three inks actually produce a muddy brown and must be combined with black (K) ink to produce a true black. (K is used instead of B to avoid confusion with blue.) Combining these inks to reproduce color is called four-color process printing.

The subtractive (CMY) and additive (RGB) colors are complementary colors. Each pair of subtractive colors creates an additive color, and vice versa.