The number of colors perceived by dichromats when appreciating art paintings under standard illuminants

The chromatic content and diversity experienced by normal observers when observing art paintings vary with the spectral composition of the illumination and can be estimated by quantities such as color rendering indices and the number of discernible colors. Can these estimates be extended to color deficient observers? The aim of this work was to investigate how the number of discernible colors perceived by dichromats in art paintings varies when the paintings are rendered under CIE standard illuminants. Hyperspectral images of eleven oil paintings were collected at the museum and the number of discernible colors perceived by trichromats and dichromats under 55 CIE illuminants was estimated for each painting. It was found that the number of discernible colors varies considerably across illuminants for all classes of observers analyzed. When comparing with CIE standard illuminant A, substantial enhancement of about 14%, 30%, 20% and 10%, could be obtained with specific illuminants for trichromats, protanopes, deuteranopes and tritanopes, respectively. These results suggest that color deficient observers may require personalized lighting conditions.