Evaluating the perceived brightness of chromatic stimuli with backgrounds of varying luminance

Abstract

Reproducing near‐gamut colors on an emissive display often causes them to appear brighter than an achromatic color of the same luminance. This phenomenon can be explained by the Helmholtz–Kohlrausch (H–K) effect, which describes an increase in perceived brightness when increasing the chroma of a stimulus. Although recent studies have attempted to incorporate the H–K effect into their modeling, none of these studies have directly explored how the perception of chromatic stimuli changes with background luminance. In this article, we present results from a psychophysical brightness‐matching experiment conducted across different levels of background luminance. The experimental results show the magnitude of the H–K effect upon simultaneous lightness contrast for high chroma colors. We, then, compare our results to CAM16 and other published models that propose modifications to CAM16 to account for the H–K effect. The findings reveal that CAM16 overestimates the perceived rate of lightness change by more than double for highly saturated, low luminance colors with increasing background luminance levels. Despite the progress made in incorporating the H–K effect into models, our study indicates the need for further data to establish a more accurate and robust modeling of this phenomenon.