The visible spectrum of colors. See CCRS for more information on the electromagnetic spectrum. In printing a color document from a computer display, the printer must translate additive colors into corresponding combinations of subtractive colors. The Munsell color code is the internationally accepted standard for describing color quantitatively. The use of color on maps is much more than simply a way to construct a legend.
Color carries visual meaning, it directs attention, it can emphasize or obscure features.
Thus, color selection is an important element of map design. The human eye can distinguish tens of 1000s of different colors, but only 20-30 gray tones. Super VGA monitors can display up to 256 simultaneous colors from a total of several million possibilities. More advanced monitors can display still more colors. On a static map, however, the eye cannot relibly match more than 16-20 simple colors from the legend with the map.