Performance of melanopsin-based spatial brightness metrics

Traditional photometric measures fail to accurately estimate perceived brightness, leading to the development of spatial brightness as a concept to quantify overall scene brightness. Recent research has revealed that melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs), in addition to cone cells, contributes to brightness perception, and new metrics have been developed to predict cone and melanopsin-driven brightness perception. This study evaluates the performance of three melanopsin-based spatial brightness metrics through a twoalternative forced choice (2AFC) simultaneous brightness experiment involving 15 pairs of lighting conditions. Results indicate that the melanopsin-based spatial brightness metrics perform poorly, with a maximum accuracy of 50%, which is on par with chance. Future research should explore a wider range of illuminance, melanopic illuminance, and correlated colour temperatures (CCT) levels.