Chapter 5b: Color Constancy Flashcards
related color
A related color is seen only in relation to other colors.
E.g.: brown, gray – perception depends on surrounding colors.
Illuminant
The light that illuminates a surface
Color constancy
The tendency of a surface to appear the same color under a fairly wide range of illuminants
To achieve color constancy, we must discount the illuminant and determine what the true color of a surface is regardless of how it appears.
http://www.echalk.co.uk/amusements
/OpticalIllusions/colourPerception
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McCann, McKee, and Taylor Experiment (Part 1)
Each eye was seeing independent images. One eye was the reference the other the one that was manipulated.
When the illumination of the whole scene changed, the green patched reflected light that would have been perceived as GRAY if in ISOLATION. But, not so in the context of all the other colors.
The same surface illuminated by two different lights will generate two different patterns of activity in the S-, M-, and L-cones
……
From the Color of Lights to a World of Color
Physical constraints make constancy possible:
Intelligent guesses about the illuminant
Assumptions about light sources
Assumptions about surfaces
Perception
We often base perception of color on surrounding context.
Perceived color can disappear when contextual color is removed
*Picture of multicolored block in different lighting
Perception
We often base perception of color on surrounding context.
Perceived color can disappear when contextual color is removed.
- Picture of multicolored block in different lighting
- Disney uses pink pavement to make plants look greener!
Photoreceptor Density across the Retina
Diagram of photoreceptor density across the retina.
DUPLEX retina.
90 million rods, 4 million cones.
1 degree of visual angle where no RODS, only cones. Right behind center of pupil.
BLIND IN THE DARK.
Don’t look straight at faint stars.
Other fun factoids about color…
Color in the periphery is an Illusion!
- Guess the color of upcoming cars…
- Check out the amount of color in these images.
Color of the DRESS?!?
“It has to do with the tiny cones in the back of our eyeballs that perceive colors in a slightly different way depending upon our genes,” explains CNN’s Senior Medical Correspondent Elizabeth Cohen.
“I can officially confirm the color is royal blue with black trimming,” said Michelle Bastock, Roman’s fashion director, during an interview.
