VISUAL-PERCEPTION OF LUMINANCE CONTRAST - IMPLICATIONS FOR THE ASSESSMENT OF SUBJECTIVE IMAGE QUALITY

As part of a program of experimentation designed to measure the subjective quality of displayed images, the perception of simultaneous luminance contrast was considered. This involved an examination of the ability of the human visual system to discriminate between areas of differing brightness (i. e. grey shades) presented on a monochromatic crt display screen. Certain contrast-related visual illusions were found to occur, illustrating the complex nature of the perceptual processes involved and questioning the validity of accepted techniques for subjective image contrast assessment, e. g. the use of grey-scale patterns. The paper discusses these findings, their implications and possible alternative assessment techniques.