We examine the mechanism that subserves visual contour detection and particularly its tuning for the spatial frequency of contour components. We measured the detection of contours composed of Gabor micropatterns within a field of randomly oriented distractor elements. Distractors were randomly assigned one of two spatial frequencies, and elements lying along the contour alternated between these values. We report that the degree of tolerable spatial-frequency difference between successive contour elements is inversely proportional to the orientation difference between them. Spatial-frequency tuning (half-width at half-height) for straight contours is ~1.3 octaves but, for contours with a 30° difference between successive elements, drops to ~0.7 octaves. Integration of curved contours operates at a narrower bandwidth. Much orientation information in natural images arises from edges, and we propose that this narrowing of tuning is related to the reduction in interscale support that accompanies increasing edge curvature.
© 1998 Optical Society of America
(330.4060) Vision, color, and visual optics : Vision modeling
(330.4270) Vision, color, and visual optics : Vision system neurophysiology
(330.5510) Vision, color, and visual optics : Psychophysics
(330.6110) Vision, color, and visual optics : Spatial filtering
(330.7310) Vision, color, and visual optics : Vision
S. C. Dakin and R. F. Hess, "Spatial-frequency tuning of visual contour integration," J. Opt. Soc. Am. A 15, 1486-1499 (1998)