OSA uniform color scale samples: A unique set

Abstract

AbstractThe Optical Society of America, in early 1977, published a set of uniformly scaled coor samples based on specifications developed after long years of study by its Committee on Uniform Color Scales. The model for arranging and specifying the samples is based on an octahedral unit which consists of a cluster of 12 colors equally different from a central color and from each of its nearest neighbors. This space lattice, extended to accommodate all samples that can be produced within the gamut of present‐day colorants, is described, together with the adopted system of notation. The lattice provides three sets of square grids and four sets of triangular grids that correspond to the seven pairs of parallel faces of a cuboctahedron. Horizontal, vertical, and oblique cleavage planes through the lattice are described and illustrated. The OSA‐UCS set consists of 558 samples: 424 represent a regular 2‐unit sampling of OSA‐UCS committee space; 134 additional samples are provided in the much used, near‐neutral, central‐lightness region of color space. The set is unique because each sample in the regular set is represented in six different uniform color scales. These appear as linear arrays that pass in six different directions through each sample. The samples are intended for use by artists and designers as well as by scientists. With a relatively small number of samples, material is provided for constructing color scales and charts with colors uniformly spaced in six directions in any chosen part of color space. The OSA‐UCS set provides a “storehouse of color‐contrast information in efficient form.” It provides useful color research material such as has never before been available.