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This document explores the front-end computations underlying human vision, focusing on models and representations utilized in visual processing. Highlighting key references from experts like DeValois, Hubel, and Malik, it discusses the structure of monocular and binocular visual fields, cone and rod functions, and modeling simple cells through Gaussian derivatives. It also emphasizes the significance of orientation energy in visual perception, detailing methodologies such as K-means clustering of filter responses and the mapping from retina to cortical areas, enriching our understanding of vision complexities.
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Front-end computations in human vision Jitendra Malik U.C. Berkeley References: DeValois & DeValois,Hubel, Palmer, Spillman &Werner, Wandell
Monocular Visual Field: 160 deg (w) X 135 deg (h)Binocular Visual Field: 200 deg (w) X 135 deg (h)
Modeling simple cells • Elongated directional Gaussian derivatives • 2nd derivative and Hilbert transform • L1 normalized for scale invariance • 6 orientations, 3 scales • Zero mean
Orientation Energy • Gaussian 2nd derivative and its Hilbert pair • Can detect combination of bar and edge features; also insensitive to linear shading [Perona&Malik 90] • Multiple scales
Textons (Malik et al, IJCV 2001) • K-means on vectors of filter responses
Texton Histograms Chi square test: i 0.1 j k 0.8