Illuminant metamerism potentiality of metameric pairs

Abstract

Indices for describing the degree of metamerism are based on either the deviation of the spectra of a metameric pair or the colour difference of the pair under test conditions. The magnitude of illuminant metamerism is commonly evaluated by measuring the colour difference under the test illuminant. The calculated colour differences absolutely vary with the selected test illuminants, so the measured (special) index of metamerism could be considered as a test‐illuminant‐dependent value. The spectral‐based indices of metamerism act as a single‐number value, but most of them are criticised for their poor correlation with visual assessment. In this paper, a general metric is developed for evaluating the upper limit of the degree of illuminant metamerism. The suggested approach combines the advantages of general and special indices, avoiding their drawbacks at the same time. The performance of the formula is analysed in a number of numerical experiments, as well as by practical testing.