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Human vision . Jitendra Malik U.C. Berkeley. Cerebral Cortex. Monocular Visual Field: 160 deg (w) X 175 deg (h) Binocular Visual Field: 200 deg (w) X 135 deg (h). Cones and Rods. Receptor density vs eccentricity. Processing in the retina. ON and OFF cells in retinal ganglia.
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Human vision Jitendra Malik U.C. Berkeley
Monocular Visual Field: 160 deg (w) X 175 deg (h)Binocular Visual Field: 200 deg (w) X 135 deg (h)
The visual system performs • Measurement of light and spatial relations • Perceptual Organization • Active interaction with environment
Measurement of light and spatial relations • Measuring light • Sensitivity over high dynamic range • Gain control results in “Weber Machine” • Sensitivity to contrast rather than absolute luminance level—discounting the illuminant • Measuring Spatial relations • Contrast sensitivity function • Vernier Acuity
Weber Contrast Cw = ΔL/LMichelson Contrast CM = (Lmax – Lmin)/2 Lmean
The debate..(and sometimes both were right !) • Helmholtz argued that perception is unconscious inference. Associations are earned through experience. • Hering proposed physiological mechanisms—opponent color channels, contrast mechanisms, conjunctive and sisjunctive eye movements..
The Twentieth Century.. • The Gestalt movement emphasized perceptual organization. • Grouping • Figure/ground • Configuration effects on perception of brightness and lightness
Gibson’s ecological optics (1950) • Emphasized richness of information about shape and surface layout available to a moving observer • Optical flow • Texture Gradients • ( and the classical cues such as stereopsis etc)
