Fundamental Lightness and Brightness Scales

Modeling lightness and brightness is a complex process since they are not simple functions of luminance, and they depend on additional properties of the stimulus and viewing conditions, as well as visual adaptation. Several XYZ-based metrics were developed to model lightness and brightness, which carry the disadvantages of the XYZ-based system. This study aims to develop one-dimensional brightness and lightness scales directly built based on cone fundamentals to account for the underlying physiology of the human visual system and individual differences. The proposed lightness and brightness scales are called <i>FLS</i> for <b>F</b>undamental <b>L</b>ightness <b>S</b>cale and <i>FBS</i> for <b>F</b>undamental <b>B</b>rightness <b>S</b>cale, respectively. The Helmholtz-Kohlrausch effect was included in using the <i>G</i>₀ luminance the Bartleson-Breneman effect was modeled using an optimized power function, and the Stevens effect was included in using terminal brightness. Evaluation of the FLS and FBS scales was completed using seven data sets. In comparison to other models, the FLS and FBS have a good performance on all data sets.