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Human Visual Systems and Perception C. Edward Chow.

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Presentation on theme: "Human Visual Systems and Perception C. Edward Chow."— Presentation transcript:

1 Human Visual Systems and Perception C. Edward Chow

2 mccchow2 Image in Human Eye

3 mccchow3 Rod and Cone Cell Distribution

4 mccchow4 Contrast Illusion

5 mccchow5 Demystify Illusion with Mach Bend Effect

6 mccchow6 Spatial Frequencies Image can be considered as superposition of gratings of different spatial frequencies (cycles/degree).

7 mccchow7 Contrast Impact

8 mccchow8 Visual Acuity Visual acuity: the smallest angular separation at which the individual lines can be distinguished. Depend on contrast ratio and keenness of your eyes. 1.7’ is normal assumption= 60/(2*1.7’)~18 cycles/degree Visual acuity: the smallest angular separation at which the individual lines can be distinguished. Depend on contrast ratio and keenness of your eyes. 1.7’ is normal assumption= 60/(2*1.7’)~18 cycles/degree

9 mccchow9 Color Representation Three-Receptor Model

10 mccchow10 Perception Representation

11 mccchow11 Tristimulus Curves Devise a system with simple numbers to represents all colors. (How about all positive numbers?) x,y,z are proportion of X primary, Y primary, Z primary (supersaturated red, green and blue) x=X/(X+Y+Z); y=Y /(X+Y+Z); z=1-x-y Devise a system with simple numbers to represents all colors. (How about all positive numbers?) x,y,z are proportion of X primary, Y primary, Z primary (supersaturated red, green and blue) x=X/(X+Y+Z); y=Y /(X+Y+Z); z=1-x-y

12 mccchow12 CIE {X,Y,Z} system CIE: Commission Internationale de I’Eclairage, The International commission on color standards) Figure 2.17b shows the corresponding amount of primaries needed to match all wavelengths of visible spectrum. CIE: Commission Internationale de I’Eclairage, The International commission on color standards) Figure 2.17b shows the corresponding amount of primaries needed to match all wavelengths of visible spectrum.

13 mccchow13 1931 CIE Chromaticity Diagram

14 mccchow14 Color Coordinate System Conversion

15 mccchow15 Transformation from NTSC


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