The role of lightness perception in determining the perceived contrast of real world scenes

Abstract

We investigate the impact of the background luminance upon the perceived image quality of real world scenes. To do so, we generate a set of small image patches that span the full range of mean luminance values and contrasts that may be displayed upon a monitor with a finite luminance range. Subjects viewed the images on a uniform black, grey or white surround and were asked to rate the perceived quality on a scale from 0 to 9. We find that that the maximum image quality scores occur for images with a mean luminance of less than half, consistent with the image being passed through a compressive non-linearity before contrast is computed. Moreover, the maximum image quality scores occur at lower mean luminance levels when the background luminance is darker, a pattern consistent with investigations into lightness perception. We conclude that models of contrast perception require an adaptive model of lightness perception. However, we also note the considerable challenge of developing a model of lightness perception that can generalize to any given display configuration.