Measuring perceptual contrast in a multi-level framework

In this paper, we propose and discuss some approaches for measuring perceptual contrast in digital images. We start from previous algorithms by implementing different local measures of contrast and a parameterized way to recombine local contrast maps and color channels. We propose the idea of recombining the local contrast maps and the channels using particular measures taken from the image itself as weighting parameters. Exhaustive tests and results are presented and discussed, in particular we compare the performance of each algorithm in relation to perceived contrast by observers. Current results show an improvement in correlation between contrast measures and observers perceived contrast when the variance of the three color channels separately is used as weighting parameter for local contrast maps.