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Human vision

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

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  1. Human vision Jitendra Malik U.C. Berkeley

  2. Cerebral Cortex

  3. Monocular Visual Field: 160 deg (w) X 175 deg (h)Binocular Visual Field: 200 deg (w) X 135 deg (h)

  4. Cones and Rods

  5. Receptor density vs eccentricity

  6. Processing in the retina

  7. ON and OFF cells in retinal ganglia

  8. Visual Processing Areas

  9. The visual system performs • Measurement of light and spatial relations • Perceptual Organization • Active interaction with environment

  10. 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

  11. Threshold vs. Intensity

  12. Weber Contrast Cw = ΔL/LMichelson Contrast CM = (Lmax – Lmin)/2 Lmean

  13. Why contrast is the right variable..

  14. Simultaneous Contrast

  15. Mach Band

  16. A Mach Band in 1D profile

  17. Craik-O’Brien-Cornsweet

  18. Contrast Sensitivity Function at different luminances

  19. Receptor density vs eccentricity

  20. CSF as function of eccentricity

  21. Cortical Magnification Factor

  22. Mapping from Retina to V1

  23. Physiological Optics 1840-1894

  24. The Empiricist-Nativist debate

  25. 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..

  26. The Twentieth Century.. • The Gestalt movement emphasized perceptual organization. • Grouping • Figure/ground • Configuration effects on perception of brightness and lightness

  27. Grouping factors

  28. Grouping Factors

  29. The Figure-Ground Problem

  30. Transparency

  31. Wallach’s Brightness ratios

  32. 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)

  33. Measuring Surface Orientation

  34. Accomodation

  35. Depth of field of human eye

  36. Convergence

  37. Convergence angle vs. distance

  38. Binocular Stereopsis

  39. Optical flow for a pilot

  40. Some Pictorial Cues

  41. Shading

  42. Cast Shadows

  43. Geometry of cast shadows

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