MacAdam ellipse

This question was first approached by a number of researchers in the 1930s, and their results were formalized in the specification of the CIE XYZ color space.

This particular question was considered by researchers dating back to Helmholtz and Schrödinger,[3] and later in industrial applications,[4] but experiments by Wright and Pitt,[5] and David MacAdam provided much-needed empirical support.

It was found by MacAdam, however, that the standard deviation of the matches made by the observer fell into an ellipse on the CIE 1931 chromaticity diagram.

[8] The original experiment carried out by MacAdam limited the field of view to be 2°,[1] essentially giving the ellipse estimations at the foveal vision.

Using a Fisher information metric, da Fonseca et al. [14] investigated the degree to which MacAdam ellipses can be derived from the response functions of the retinal photoreceptors.

It was demonstrated that photoreceptor absorption properties explain ≈ 87% of the variance of human color discrimination ability, as tested by previous behavioral experiments.