The first use of strict substitution colorimetry for collecting data on threshold perceptual color differences in humans.

Colorimetry is a technology capable of quantifying human color perception. It is of great importance in vision science and color psychology, helping to develop color standards, color measurement devices, and color management systems. Nowadays, the basic method of colorimetry implies comparing two simultaneously presented stimuli (semi-fields). In this case, two different retinal areas are exposed to colors to be matched. This drawback is not inherent to the strict substitution method, which involves comparing the perception of two color stimuli alternately presented on the same area of the retina. This method was proposed almost 70 years ago by Bongard and Smirnov, but has not been developed since then because of its apparent complexity. Today, light sources with a controlled emission spectrum have come into use so much that it becomes much easier to make a colorimetric installation that implements the strict substitution method. In this paper, we propose a comprehensive procedure for implementing strict substitution colorimetry, aimed at collecting data on threshold perceptual color differences in humans. Our pilot experimental results show good consistency and repeatability. We believe that the suggested technique will allow collecting the lacking color difference data at the periphery of the wide color gamut (WCG) as well as for extremely high dynamic range (HDR) colors.