The CIE1976 L*a*b* space is a color opponent space that aims to be perceptually uniform, so that one unit in the space corresponds to a just noticeable difference in color. The L* dimension corresponds to visual lightness, while the a* corresponds approximately to redness/greenness, while b* corresponds approximately to yellowness/blueness. It is the direct basis of the CIE Delta E 76, and the base for latter, more refined color difference metrics such as CIE Delta E 94 and CIE Delta E 2000, as well as basis of the DIN99 Delta E color space. While it is approximately perceptually uniform, it is not perfect, showing some hue linearity problems in the blue region, and exaggerating color distances somewhat for more saturated colors.

It is a white relative space, where the reference white has the L*a*b* value 100,0,0. The typical assumption is that an observer is adapted to the white reference, so that the L*a*b* coordinates correspond to the colors relative to that white.

Details of white point configuration.

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