Human Visual Systems and Perception

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# Human Visual Systems and Perception - PowerPoint PPT Presentation

Human Visual Systems and Perception. C. Edward Chow. Image in Human Eye. Rod and Cone Cell Distribution. Contrast Illusion . Demystify Illusion with Mach Bend Effect. Spatial Frequencies. Image can be considered as superposition of gratings of different spatial frequencies (cycles/degree).

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### Human Visual Systems and Perception

C. Edward Chow

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

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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

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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

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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.

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