Colors combine by adding color spectra
Light adds to black.
Source: W. Freeman
Slide 12
CRT phosphors
multiple projectors
Slide 13
Additive color mixing:
The spectral power distribution of the mixture is the sum of the spectral power distributions of the components.
Figure from B. Wandell, 1996
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Colors combine by multiplying color spectra.
Pigments remove color from incident light (white).
Source: W. Freeman
Slide 15
Printing on paper
Crayons
Photographic film
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Measuring color
Spectral power distributions
Color mixing
Color matching experiments
Color spaces
Uniform color spaces
Perception of color
Human photoreceptors
Environmental effects, adaptation
Using color in machine vision systems
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Important to reproduce color reliably
Commercial products, digital imaging/art
Only a few color names recognized widely
English ~11: black, blue, brown, grey, green, orange, pink, purple, red, white, and yellow
We need to specify numerically.
Question: What spectral radiances produce the same response from people under simple viewing conditions?
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Goal: find out what spectral radiances produce same response in human observers.
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Foundations of Vision, by Brian Wandell, Sinauer Assoc., 1995
After Judd & Wyszecki.
Observer adjusts weight (intensity) for primary lights (fixed SPD’s) to match appearance of test light.
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Color matching experiments
Goal: find out what spectral radiances produce same response in human observers.
Assumption: simple viewing conditions, where we say test light alone affects perception
Ignoring additional factors for now like adaptation, complex surrounding scenes, etc.
Slide 21