Title: Perceived Image Contrast and Observer Preference I. the Effects of Lightness, Chroma, and Sharpness Manipulations on Contrast Perception

A large-scale investigation into the perception of contrast in color images was performed. Psychophysical experiments were performed to determine the influence of image lightness, chroma, and sharpness transforms on perceived image contrast and observer preference. The influence of these transforms on perceived contrast was investigated separately by independent soft-copy, paired-comparison tests of contrast perception and image preference. The perception of contrast across transformations was also investigated, as was the perception of image contrast relative to the most preferred image manipulation. In all, four experiments of contrast perception and image preference were performed by at least thirty-two observers each. Results of the lightness, chroma, and sharpness-contrast experiments indicate perceived image contrast is a function of multiple image characteristics as opposed to simply being a function of the dynamic range of image intensity. In the lightness-contrast experiments, images of identical white and black points were scaled to have significant differences in contrast based on their manipulations from the