Number of Perceivable Object Color Stimuli

M. Brill, in his comments "Maximum number of discriminable colors in a region of uniform color space,' offers a different calculation method from that used by R. G. Kuehni in 'How many object colors can we distinguish?," one based on close-packing of just noticeable difference spheres. The number per just noticeable difference (JND) sphere is lower than that derived in Kuehni's study. Based on the resulting number of close-packed JND spheres in the CIECAM02/D65 object color solid and Brill's described multiplier of 5.923 potential stimuli within a JND sphere, the resulting number of distinguishable color stimuli is 9.114 million. (C) 2016 Wiley Periodicals, Inc. Col Res Appl, 41, 522, 529, 2016; Published Online in Wiley Online Library (wileyonlinelibrary. com).