lightness, chroma, hue (LCH)

The L*C*H* color model is based on the colorimetric quantities brightness (lightness), chrominance (chrominance) and hue(hue).

The L*C*H* color space corresponds to the Lab color model, with the difference that in the L*C*H* color model polar coordinates are used instead of rectangular coordinates. The L*C*H* model is similar to the HSV color model, but it has a cylindrical structure. The brightness axis is the center axis of the L*C*H* cylinder. The hue is represented by the angle of the polar vector and is given in degrees. For red, the angle of the polar vector is 0 degrees, for yellow 90 degrees, for green 180 degrees and for blue 270 degrees. The color saturation determines the length of the color vector. The achromatic value is in the center of the circular representation.

The L*C*H* color model is not very common. It was standardized in 1976 by the Commission Internationale d`Eclairage( CIE) and is used in research and quality assurance.