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# Spatial vision i revised jan 25 2011

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Presentation for Visual perception I course

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### Spatial vision i revised jan 25 2011

1. 1. Definition of Contrast
2. 9. Fourier Analysis <ul><li>Square wave = Sum of sine waves </li></ul><ul><li>Square wave = Fundamental sine wave + harmonics </li></ul><ul><li>Fundamental sine wave is a wave with the same frequency as the square wave </li></ul><ul><li>Third harmonic is a sine wave with 3 times the square wave </li></ul><ul><li>Fifth harmonic is a sine wave with 5 times the frequency of the square wave </li></ul>
3. 12. Modulation Transfer Function <ul><li>Object Contrast-> Lens -> Image contrast </li></ul><ul><li>MTF = Image Contrast/ Object Contrast </li></ul><ul><li>MTF = 1.0 for an ideal lens (or system) </li></ul><ul><li>MTF is determined by frequency to obtain a graph. </li></ul>
4. 13. Modulation Transfer Function (MTF) Frequency Object Contrast Image Contrast MTF 2 10 8 0.80 5 9 7.5 0.83 8 8.7 6.3 0.72 10 7.5 5.2 0.69 15 6.3 3.8 0.60 18 5.2 2.1 0.40 25 4.2 1.5 0.36 30 4 0.9 0.23 40 4 0.7 0.18 50 3.8 0.4 0.11 60 3.6 0.33 0.09
5. 15. Contrast Sensitivity Function(CSF)
6. 39. Ganglion cell Receptive Field
7. 40. Ganglion cell receptive field
8. 41. Ganglion cell receptive field
9. 42. Ganglion cell response to diffuse illumination
10. 43. Ganglion cell response to spatial grating
11. 44. Mach bands Dark band Bright band
12. 45. Mach bands
13. 46. Recognition Acuity <ul><li>Snellen </li></ul><ul><li>HOTV </li></ul><ul><li>LEA </li></ul><ul><li>Patti Pics </li></ul>
14. 47. LEA Symbols
15. 48. Patti Pics
16. 49. HOTV Test
17. 50. Resolution Acuity <ul><li>Tumbling E </li></ul><ul><li>Landolt C </li></ul><ul><li>Broken Wheel </li></ul>
18. 51. Broken Wheel test
19. 52. Tumbling E
20. 53. Landolt C
21. 54. Minimum detectable acuity
22. 56. Hyperacuity <ul><li>Vernier </li></ul><ul><li>Alignment test </li></ul><ul><li>Tilt test </li></ul>