Perception of high-contrast blurred edges

Observer sensitivity to edge blur has been examined by experimental measure ments of threshold blur as a function of contrast. An extension of previous results from Watt and Morgan for high-contrast blur edges is discussed and analyzed. We propose a psychophysical test based on a two-alternative forc ed choice test. The results found for three adult observers show a comparab le behavior. A tendency for the blur threshold to reach an average value as contrast increases is mainly discussed. These results complement previous ones from other authors for which low- and intermediate-contrast ranges wer e analyzed. The observed behavior suggests a need to improve algorithms for image quality assessment, extending the actual range of contrast values to high-contrast ones. (C) 2001 Academic Press.