CIE Color Systems

CIE Color Systems The CIE, or Commission Internationale de l’Eclairage (translated as the International Commission on Illumination), is the body responsible for international recommendations for photometry and colorimetry.

In 1931 the CIE standardized color order systems by specifying the light source (or illuminants), the observer and the methodology used to derive values for describing color.

The CIE system characterizes colour by a luminance Y and two colour coordinates x and y which specify the point on the chromatic diagram. This system offers more precision in colour measurement than do the Munsell system because the parameters are based on the spectral power distribution of the light emitted from a coloured object and is factored by sensitivity curves which have been measured for the human eye.

Based on the fact that the human eye has three different types of color sensitive cones, the response of the eye is best described in terms of three "tristimulus values". However, once this is accomplished, it is found that any color can be expressed in terms of the two color coordinates x and y.

The colors which can be matched by combining a given set of three primary colors (such as the blue, green, and red) are represented on the chromaticity diagram by a triangle joining the coordinates for the three colors.

The diagram given below represents the  mapping of human color perception in terms of two CIE parameters x and y. The spectral colors are distributed around the edge of the "color space" as shown, and that outline includes all of the perceived hues and provides a framework for investigating color.

The CIE Color Systems utilize three coordinates to locate a color in a color space. These color spaces include:

• CIE XYZ

• CIE L*a*b*

• CIE L*C*h°