Perceptually motivated model for predicting banding artefacts in high-dynamic range images

Abstract

Banding is a type of quantisation artefact that appears whena low-texture region of an image is coded with insufficient bit-depth. Banding artefacts are well-studied for standard dynamicrange (SDR), but are not well-understood for high dynamic range(HDR). To address this issue, we conducted a psychophysical ex-periment to characterise how well human observers see band-ing artefacts across a wide range of luminances (0.1 cd/m2–10,000 cd/m2). The stimuli were gradients modulated along threecolour directions: black-white, red-green, and yellow-violet.The visibility threshold for banding artefacts was the highest at0.1 cd/m2, decreased with increasing luminance up to 100 cd/m2,then remained at the same level up to 10,000 cd/m2. We used theresults to develop and validate a model of banding artefact detec-tion. The model relies on the contrast sensitivity function (CSF)of the visual system, and hence, predicts the visibility of bandingartefacts in a perceptually accurate way.