Optimum display luminance depends on white luminance under various ambient illuminance conditions

This paper reports display luminance levels for good visibility under nine ambient illuminance conditions (50, 100, 200, 500, 1000, 2000, 5000, 10,000, and 20,000 lx) for a given white luminance level, chosen from five candidates (100, 200, 500, 1000, and 2000 cd/m(2)), through a psychophysical experiment. This work reveals that the luminance levels for good visibility increase as the maximum white luminance of the display increases. The white luminance dependency of display luminance is caused by the fact that the human visual system adapts to the maximum white luminance and evaluates the brightness of the display based on it. Based on the experimental results, an appropriate luminance zone under various illuminance conditions is proposed. The appropriate luminance zone varies with the maximum white luminance of the displays. This may be understood to mean that there is no absolute luminance level under a given lighting condition. To solve this issue, a new method is proposed to determine optimum luminance levels by considering both visibility and power consumption. By the proposed method, it is reported that the optimum maximum luminance lies between 200 and 500 cd/m(2) for indoor use (below 500 lx). These results were verified by young adults with normal vision. (c) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.