Abstract

Each color chip of the OSA Uniform Color Scales set (1) is intended to represent a color which, under the appropriate viewing conditions, is subjectively equidistant from its nearest neighbors in a 3-dimensional Euclidean space. To the extent this is so, the 424 chips of the set define -- and at the same time sample -- a space that is isotropic with respect to color differences. The three dimensions of the OSA space, called L, j, and g, permit the color chips to be labeled with triplets of values that can be positive or negative relative to 0,0,0, for which there is a chip intended to be a middle gray. L represents a lightness axis, ranging from very dark at the bottom to very light at the top. J and g are chromatic axes (roughly yellow(+)/blue(-) and green(+)/red(-) respectively); these are orthogonal to each other and to the L axis.

© 1987 Optical Society of America