This is an elliptical region on the CIE chromaticity diagram that contains all the colors that are indistinguishable to the average human eye, from the color at the center of the ellipse. Adjacent ellipses are “just distinguishable” in terms of color. This system is used to refine the binning process of LED colors. Slight color differences in the appearance of LED light are measured in MacAdam ellipses or steps.
