HSV
Short for Hue, Saturation, and Value it is a color model that is often used in place of the RGB color model in graphics and paint programs. In using this color model, a color is specified then white or black is added to easily make color adjustments. HSV may also be called HSB (short for hue, saturation and brightness).
See "The Science of Color" in the Did You Know... section of Webopedia.
See also Webopedia's Digital Camera Quick Reference.


