November 2018
Spotlight Summary by Manuel Spitschan
Color appearance model for self-luminous stimuli
Aside from “too bright” or “not bright enough,” how bright is the screen you’re reading this article from? This question—predicting how bright a self-luminous object appears—is at the heart of this recent paper by Hermans, Smet, and Hanselaer. Brightness is not a physical quantity and any model for how bright the radiance emitted or reflected from an object appears needs to take this into consideration. For reflecting objects, the CIECAM02 appearance model is widely used, but it does not extend to self-luminous objects such as screens or light sources. Hermans et al. develop an empirically validated model to calculate, for self-luminous objects, the four perceptual attributes colorfulness, brightness, saturation, and “amount of neutral,” starting from the excitation of the cones in the human eye and including a chromatic and luminance adaptation. In addition, they propose a novel brightness unit: 1 bright corresponds to a self-luminous object (diameter 10°) with an equal-energy spectrum and a luminance (in CIE 2006) of 10 cd/m2 seen against a dark background. The new CAM18sl model represents an exciting development in the field of brightness perception, and seems extendable enough to the recently reported contributions of melanopsin to brightness and to rod contributions in the mesopic range.
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Article Information
Color appearance model for self-luminous stimuli
S. Hermans, K. A. G. Smet, and P. Hanselaer
J. Opt. Soc. Am. A 35(12) 2000-2009 (2018) View: HTML | PDF