1. The Visual System and Visual Performance

2. The Visible Spectrum

3. 3 vision.ppt Anatomy of the Eye Illustration by Mark Ericksen, St. Luke’s Cataract and Laser Center, StLukesEye.com

4. 4 vision.ppt The Eye (2) lCornea  Protection  Focusing lAqueous Humor  Shape  Nutrition lIris  Light control  Focusing

5. 5 vision.ppt The Eye (3) lLens  Focusing  Accommodation lVitreous Humor  Shape lRetina  Rods: black & white, night vision  Cones: color, day vision  Fovea: sharpest vision (concentration of cones)

6. 6 vision.ppt The Eye (4) lOptic Nerve  Nerve signals to brain  Optic Disk: blind spot lEye Muscles  Eye movement  Convergence

7. 7 vision.ppt NEAR AND FARSIGHTED EYE

8. 8 vision.ppt DENSITY OF RODS AND CONES

9. 9 vision.ppt Visual Performance lBrightness lVisual Angle lVisual Acuity lColor lVisual Field

10. 10 vision.ppt Brightness lRelative amount of light reflected from an object produces a sensation of lightness or brightness. lBrightness is related to the luminance of light as well as a subjective response to color

11. 11 vision.ppt Luminous Intensity

12. 12 vision.ppt Luminous Flux

13. 13 vision.ppt Illuminance

14. 14 vision.ppt Illuminance v. Luminance lIllumination/Illuminance: The amount of light striking any point on the inside surface of a sphere surrounding the light source (Luminous flux/unit area)  Foot candle: 1 lumen/square foot  Lux: 1 luman/square meter lLuminance: The amount of light per unit area leaving (reflected from) a surface  Foot Lamberts: 1 lumen/square foot  Candelas/square meeter

15. 15 vision.ppt Luminance Note: 1 foot-Lambert (ft-L) = 0.929 mL, so 1 ft-L ~ 1 mL.

16. 16 vision.ppt Luminance (2) lThreshold of detectability 1 x 10 -6 mL lThreshold of pain 3 x 10 4 mL lLimits to discriminability 3 - 4 levels

17. 17 vision.ppt Lightness

18. 18 vision.ppt

19. Contrast Sensitivity 19 vision.ppt the luminance of pixels is varied sinusoidally in the horizontal direction. The spatial frequency increases exponentially from left to right. The contrast also varies logarithmically from 100% at the bottom to about 0.5% at the top. The luminance of peaks and troughs remains constant along a given horizontal path through the image. If the detection of contrast was dictated solely by image contrast, the alternating bright and dark bars should appear to have equal height everywhere in the image. However, the bars seem to be taller in the middle of the image.

20. 20 vision.ppt Visual Angle (minutes of arc) Visual Angle = tan -1 H/D

21. 21 vision.ppt Visual Angle of Familiar Objects ObjectDistanceVisual Angle Sun 93,000,000 mi30’ Moon240,000 mi30’ Quarterarm’s length2° Quarter90 yd1’ Quarter3 mi1” Lowercase pica typereading distance13’

22. 22 vision.ppt Cumulative Probability of Detection

23. 23 vision.ppt

24. Acuity 24 vision.ppt

25. 25 vision.ppt Minimum Separable Acuity lAlso called gap resolution lSmallest space eye can detect between parts of a target (visual object).

26. 26 vision.ppt Minimum Separable Acuity as Function of Contrast

27. 27 vision.ppt Minimum Perceptible Acuity lAlso called spot detection. lEye’s ability to detect smallest possible target.

28. 28 vision.ppt Minimum Perceptible Acuity as Function of Contrast and Background Luminance

29. 29 vision.ppt Vernier Acuity lSmallest lateral displacement of one line from another that can be detected.

30. 30 vision.ppt Vernier Acuity as Function of Background Luminance

31. 31 vision.ppt Color lAttributes  hue: red, green, blue …  saturation: vividness of hue  brightness: luminance lRelative discrimination  thousands of distinct colors lAbsolute discrimination  24 distinct colors  recommended: 9

32. HUE 32 vision.ppt

33. Absolute discrimination 0 33 vision.ppt

34. 34 vision.ppt

35. Absolute discrimination 1 35 vision.ppt

36. 36 vision.ppt

37. Absolute discrimination 2 37 vision.ppt

38. Relative discrimination 38 vision.ppt

39. List of colors lhttp://en.wikipedia.org/wiki/List_of_colors 39 vision.ppt Shades of blue Alice blueAzureBaby blueBlueCerulean blue Chinese blue Cobalt blue Columbia blue Cornflower blue Dark blueDenim Dodger blue Indigo Internationa l Klein Blue Light blue Midnight blue Navy bluePeriwinkle Persian blue Powder blue Prussian blue Royal blueSapphireSteel blueUltramarine Air Force blue Egyptian blue Electric blue Maya Blue Medium blue Sky blue

40. Visual Field

41. 41 vision.ppt Visual Impairments Myopia :Nearsightedness Hyperopia :Farsightedness Presbyopia :Loss of accommodation Night Blindness :Reduced rod vision Color Blindness :Inability to discriminate Tunnel Vision : Reduced field of view

42. 42 vision.ppt Other Factors Affecting Visual Performance lContrast: optimum level exists lIllumination: optimum level exists lTime: positive relationship lLuminance Ratio: see contrast

43. 43 vision.ppt Other Factors Affecting Visual Performance (2) lGlare: negative relationship lMovement: negative relationship lAge: negative relationship lDrugs: some drugs impair vision

44. + 44 vision.ppt

45. 45 vision.ppt

46. 46 vision.ppt

47. 47 vision.ppt

48. 48 vision.ppt

49. 49 vision.ppt

50. 50 vision.ppt

51. 51 vision.ppt

52. 52 vision.ppt