Colorimetric data for samples of OSA uniform color scales

Colorimetric specifications and measured values of one of the sets of cards issued by the Optical Society of America for its Committee on Uniform Color Scales are reported. In addition to the CIE values for illuminant D65 and color-mixture data for 10° observing fields, the corresponding L,j,g notations of the committee are also given. The average discrepancy between the actual colors and their specifications is 14% of the intended difference between pairs of nearest neighbors of the full-step set of colors. The full-step set of 424 colors exhibits 2058 pairs of nearest neighbors. The root-mean-square deviation from the average difference, evaluated by use of the committee’s formula for color difference, is 12%. To bisect the color differences in the frequently used medium-lightness range of low-saturation colors, 134 additional colors are included in the set. Together with 13 embedded and 38 immediately adjacent colors of the full-step set, they provide 740 half-step pairs of colors. The rms deviation is 17% of their average.