PSYC 2220 Lecture Notes - Lecture 3: Subtractive Color, Color Vision, Color Blindness
23 Dec 2013
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Document Summary
The colour of a surface depends on the mix of wavelengths that reach the eye from the surface. 2. discrimination: we must be able to tell the difference between one wave-length and another. 3. appearance- we want to assign perceived colors to lights and surfaces in the world. Moreover, we want those perceived colors to go with the object (blood is red) and not to change dramatically as the viewing conditions change (blood should remain red in sun and shadow, for example). 3 types of cone photoreceptors detect the wave lengths. (s-cones 420nm, m cones 535nm, l cones. These three allow us to detetct from 400nm 700nm. Problem of univariance: the fact that an infinite set of different wave-length-intensity combinations can elicit exactly the same response from a single type of photoreceptor. One photoreceptor type cannot make colour discrimintaions based on wave-lengths. Univariance explains the lack of colour in dimly lit scenes.
