The saturation or chroma of a hue defines its intensity or purity . Terms like "weak", "strong", "brilliant", or "vivid" are often used to describe saturation.
A contrast control determines saturation: decreasing contrast adds tone (gray), while increasing contrast adds more of the hue.
Decreasing contrast adds tone and brings a color closer to gray.

Increasing contrast adds more of the hue to the color, making it more brilliant, i.e. pure hue. In the computer RGB system, this means a color would come closer to one of 8 (2^3) possible pure colors: Red, Yellow, Green/Lime, Cyan/Aqua, Blue, Magenta/Fuchsia, White, or Black.

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2007-10-21 14:13:05Z