NO ROLE FOR MOTION BLUR IN EITHER MOTION DETECTION OR MOTION-BASED IMAGE SEGMENTATION

The human contrast sensitivity function is bandpass in form for stimul i of low temporal frequency but low pass for flickering or moving stim uli. Because the loss in sensitivity to moving stimuli is large, image s moving on the retina have little perceptible high-spatial-frequency content. The loss of high-spatial-frequency content-often referred to as motion blur-provides a potential cue to motion. The amount of motio n blur is a function of stimulus velocity but is significant at veloci ties encountered by the visual system in everyday situations. Our expe riments determined the influence of high-spatial-frequency losses indu ced by motion of this order on motion detection and on motion-based im age segmentation. Motion detection and motion-based segmentation tasks were performed with either spectrally low-pass or spectrally broadban d stimuli. Performance on these tasks was compared with a condition ha ving no motion but in which form differences mimicked the perceptual l oss of high spatial frequencies produced by motion. This allowed the r elative salience of motion and motion-induced blur to be determined. N either image segmentation nor motion detection was sensitive to the hi gh-spatial-frequency content of the stimuli. Thus the change in percep tual form produced in moving stimuli is not normally used as a cue eit her for motion detection or for motion-based image segmentation in ord inary situations. (C) 1998 Optical Society of America.