A Regular Rhombohedral Lattice Sampling of Munsell Renotation Space

At the October, 1953, meeting of the OSA Committee on Uniform Color Scales there was reviewed the progress made since 1948 in experimental determinations of the rates of change of color perception with distance in the (Y,x,y) CIE color solid under various observing conditions. Similarly there was reviewed progress in devising more accurate formulas for the size of color differences perceptually evaluated. It was noted that these studies have supplied a basis for improvement in the spacing recommended in 1943 by the OSA Committee on the Spacing of the Munsell Colors. The committee voted to proceed with this adjustment of spacing and to undertake the preparation of a face-centered cubic (or regular rhombohedral) sampling of the adjusted color space in the form of color chips suitable for study by members of the committee. If the adjusted space is perceptually uniform, the rhombohedral sampling will result in an array of colors each of which, in the interior of the array, is surrounded by 12 nearest neighbors all differing from the central color by the same perceptual amount. On this account this array of colors is maximally convenient for a closing visual check of the adequacy of the experimental data used for adjusting the color space. As a first step toward production of such an array of colors in chip form, Dr. Wyszecki was asked to compute color specifications for a sampling of Munsell renotation space according to a rhombohedral space lattice of such unit size as to produce, with available colorants, about 500 colors. This paper gives the numerical results requested, together with a brief discussion of space lattices and their importance in studies of tridimensional color spacing.Deane B. Judd, ChairmanOSA Committee on Uniform Color Scales