The purpose of this research was to design and complete psychophysical experiments for scaling lightness and lightness differences for achromatic percepts above and below the lightness of diffuse white (L*=100). Below diffuse white experiments were conducted under reference conditions recommended by CIE for color difference research. Overall a range of CIELAB lightness values from 7 to 183 was investigated. Psychophysical techniques of partition scaling and constant stimuli were applied for scaling lightness perception and differences, respectively. The results indicate that the existing L* and CIEDE2000-weighting functions approximately predict the trends, but don't well fit the visual data. Hence, three optimized functions are proposed, including a lightness function, a lightness-difference weighting function for the wide range, and a lightness-difference weighting function for the range below diffuse white.
Ping-Hsu Chen, Mark D. Fairchild, Roy S. Berns, "Scaling Lightness Perception and Differences Above and Below Diffuse White" in Proc. IS&T 18th Color and Imaging Conf., 2010, pp 42 - 48, https://doi.org/10.2352/CIC.2010.18.1.art00009