The recognition and representation of edge blur: Evidence for spatial primitives in human vision

• Published in: Vision research (Oxford) Vol. 23; no. 12; pp. 1465 - 1477
• Main Authors: Watt, R.J., Morgan, M.J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1983; Elsevier Science
• Subjects: Biological and medical sciences; Discrimination (Psychology) - physiology; Edge detection; Form Perception - physiology; Fundamental and applied biological sciences. Psychology; Humans; Light; Mach bands; Male; Perception; Photometry; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Sensory Thresholds - physiology; Spatial primitives; Vernier acuity; Vision; Visual Acuity; Vernier acuity; Mach bands; Spatial primitives; Edge detection; Human; Spatial frequency; Discrimination; Coding; Vision; Visual acuity; Perception; Transduction; Signal detection; Recognition
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/0042-6989(83)90158-X

Experiments are reported that measure the precision with which observers can (a) discern the degree of blur of an edge, (b) distinguish between two different types of blur, and relate the locations of two such edges by judging their (c) misalignment or (d) separation. Three blurring functions were used, and detailed examination of the retinal stimulus in each case leads to a simple hypothesis for the visual coding of edge blur. This is interpreted in terms of a general and primitive code for the transduction of local and widespread spatial luminance changes, in which stationary points in an approximation to the second derivative are detected and localized. The phenomena of illusory brightness changes in Mach bands and the Chevreul illusion find a ready explanation in this theory.