Perception-referenced method for comparison of radiance ratio spectra and its application as an index of metamerism

Abstract

Color stimuli are termed metameric if they match in color under a set of reference conditions, such as the 1931Standard Observer and Illuminant D65, but possess radiance ratio spectra which are different. A metameric indexquantifies, in some sense, the extent to which the two spectra differ.Current CIE recommendations for evaluating metamerism include the special metamerism indices for change inilluminant [1] and change in observer. [2] These consist of, in essence, the total color difference (EE or \E*) betweenthe two stimuli under a set of conditions which differ from the reference conditions under which the two stimuli matchin color. The change in conditions is limited to either a change in illuminant (in the case of the special metamericindex for change in illuminant) or change in observer (for the special metameric index for change in observer).While there are some instances in which a single change in test conditions is of interest, there are many more forwhich several test conditions bear on the acceptability of a metameric match. For example, goods which are purchasedunder cool white fluorescent lighting, for example, would be expected to match also under other types of fluorescent