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.

Metamerism and shade sorting

“…From the theoretical point of view, a metameric pair of samples exhibits the metameric effect when the magnitudes and/ or the directions of the colorimetric shifts of individual samples in the pair are different. Peyvandi et al (2012) attempted to develop a quantitative measure for objectively describing the metameric essence of a metameric pair. This measure is referred to as IMP -its magnitude is independent of changes in illumination (test illuminants).…”

Study on metamerism degree evaluation based on wavelength sensitive cone weighting algorithm

“…Based on the usual color difference formula that gives equal weight to brightness and saturation, Wang et al believed that the effect of brightness on reflectance is much greater than the saturation on reflectance. 12 It is proposed that there should be a brightness weighting in Equation (8). According to their experimental results, when the weight for ΔL is 3, the special MI calculated is more in line with visual sensitivity of human eyes (see Equation 9)…”

“…Another type is general MIs, which are based on the essential difference between a pair of metameric spectra. General MIs are independent of light source …”

“…General MIs are independent of light source. 8 In the third edition of Colorimetry, Committee Internationale de l'Eclairage (CIE) recommends that when the pairs are not exactly matched, the tristimulus XYZ values can be corrected by the multiplicative correction, and then the MI is calculated. 9 Currently, CIE recommends calculating color difference between metameric pairs as special MI, which is widely used to evaluate the degree of metamerism.…”

A general metric for the magnitude of observer metamerism

“…Remark 1 The CIE L * C * h and CMC( l : c )/CIE94 versions of the OMP can be calculated as explained in earlier work .…”