Quantitative Relation between Chromaticity Differences and Luminance Differences*

In general, when two or more stimuli are simultaneously presented to the eye, the phenomenon referred to as “contrast” results. This contrast will be produced by differences between the stimuli, in either luminance or chromaticity, or both.Making use of the fact that veiling luminance, commonly called “glare,” destroys contrast, the authors propose the use of veiling luminance as a means for specifying the equivalence between chromaticity differences and luminance differences. The results of measurements on a large number of samples are presented, together with a practical application of the proposed method to the problem of determining how much chromaticity differences contribute to the judgment of graininess in photographic materials.