Effects of highlight luminance and spatial distribution on adaptation when viewing high dynamic range displays

Light adaptation helps maintain the perception of details and colors under different illumination levels. High dynamic range (HDR) displays enable highlights beyond diffuse white and can enhance the viewing experience, but users have experienced reduced saturation and loss of shadow details. This study investigated whether highlight luminance and spatial distribution affected light adaptation. Observers performed memory color matching and contrast-threshold adjustment tasks under 19 background conditions on a 32 inch HDR display calibrated to a diffuse white luminance of 203cd/m² and a peak luminance of 1000cd/m². The backgrounds included one standard dynamic range (SDR) reference and 18 test conditions with two highlight luminance levels (i.e., 203 and 1000cd/m²) and nine spatial distributions. The results showed that both highlight luminance and spatial distribution significantly affected adapted luminance. Scattered, individually small highlights did not alter adaptation, whereas 1000cd/m² highlights larger than 1% of the display area increased adapted luminance by being perceived as part of the background. Such an effect is likely to be more pronounced on smaller displays, where highlights occupy a larger portion of central vision.