Abstract
Recently, high-dynamic range (HDR) displays like organic light emitting display (OLED) are becoming more popular. They can display images with brightest/darkest luminance at the ratio of over 1:10^6, that yields a high fidelity of material property perception. The contrast sensitivity function (CSF) may strongly govern the quality of visual perceptions including surface property, however, it has not been investigated well in the HDR scene. Here, we investigated effects of a luminance-variegated background on CSFs measured on an OLED screen. The test stimulus was a Gabor patch on a uniform pedestal (3 deg × 6 deg in visual angle) with either of five luminance levels ranged from 0.84 to 107.2 cd/m^2. There were two conditions regarding the entire background (9.5 deg × 9.5 deg) to which observers were steadily adapted: texture and uniform conditions. In the texture condition, the background was a one-dimensional (line) texture orthogonal to the test stimulus with random luminance values, while the uniform condition background was an entirely uniform area with the pedestal luminance. The results showed reduction in lower luminance levels, particularly larger in the texture condition, indicating the prevention of rod contributions by the wide luminance range of background. Another remarkable feature is the spatial frequency profile; it showed selective reduction around the spatial frequency of background texture (0.5 cycles/deg), which implies that the measured CFSs are not simply determined by the classical Gabor-type receptive fields. Our results imply the involvement of orientation-non-selective mechanisms in the regulation of visual sensitivity in the HDR scenes.