Scaling Procedures for Specifying Color Appearance

Abstract

The world around us is often brightly colored. For various reasons it may be necessary to specify these colors precisely. One way is to describe each color in terms of the mixture of three primaries needed to match it. But this tells us only about equivalences and not about appearance. Furthermore, colorimetric matches remain stable even though appearances can change drastically with viewing conditions (1;2). We propose that hue and saturation scaling can be used to specify appearance precisely and reliably. The general techniques have been described earlier (3-5). We have examined several methodological variants to find one that is easily and reliably used, obtained "standard" functions from large groups of subjects under a variety of viewing conditions, and have tested the applicability of the technique with untrained observers. We have also used multidimensional scaling (MDS) (6;7) to derive uniform appearance diagrams (UAD) from the scaling data; from these spaces we have derived discrimination functions.