Three‐dimensional threshold of color‐difference perceptibility in painted samples: Variability of observers in four CIE color regions

Abstract In four of the five CIE color regions, the correlation of perceptibility of color differences and colorimetric measures is studied for painted samples at threshold. Sample pairs resulting in three‐dimensional color differences ranging from zero to just clearly perceptible were used. The variability of color‐difference ellipsoids is shown for single observers and for observer groups. Randomisation of mean results by a Monte‐Carlo method produces deviation ellipsoids that describe shells of uncertainty inherent in the data. Interobserver and inter‐group variability turns out to be widely covered by random noise, but the variances leave some stability of ellipsoid shapes. Color‐difference formulas should be able to predict color differences within the shells of uncertainty.