A simplified version of the MacAdam equation for color difference is presented. It is used in comparison with the Adams-Nickerson index for hypothetical colors in C. I. E. space and for colors of selected plastic samples. The two indexes disagree seriously except when the color difference involves differences in only one, and the same, chromaticity coordinate. Visual estimates of color differences shown by plastic samples show preferential agreement with the MacAdam index. The suggestion is made that this simplified MacAdam formula be given wider trial.
G. W. INGLE and L. RUDICK, "A Comparison of the MacAdam and the Adams-Nickerson Indexes of Color Differences," J. Opt. Soc. Am. 43, 501-503 (1953)