Abstract
Images appear to be blurred as its power at higher spatial frequencies is reduced. The present study examines whether the perceived blur depends on only one or both of the bright/dark (On/Off) contrast polarities. In experiments, the subjective blur of test image in which the power of either On or Off component at higher spatial frequencies is reduced was measured by matching them to reference stimuli in which both On and Off components were reduced by various degree. The test stimulus had 5 levels of blur generated by reducing high-frequency power between 20 and 100%. We found that the image appears to be markedly blurred as compared to the original when Off component is reduced, whereas little effect was observed when On component is reduced. This asymmetry is prominent for a variety of natural images, but also evident for artificial stimuli such as letters and square-wave gratings. We also found that adaptation to a texture composed of small dark dots (Off) made the subsequently presented image more blurred than adaptation to a texture of bright dots (On). These results suggest that Off component within high spatial range is the critical factor determining perceived blur.
Meeting abstract presented at VSS 2014