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3 Visual Perception
3.3 COLOR
Up to now we have ignored the wavelength of the light which produces the
visual stimulus. As this wavelength varies, the perceived color (or, more
precisely, hue) of the light changes, from red (corresponding to the longest
visible wavelength) through orange, yellow, green, and blue to violet. Mixtures
of wavelengths also give rise to perceived hues, some of which (e.g., purple)
cannot be obtained from any single wavelength. "White" (or gray) light can
also be obtained by mixing colored lights. In fact, any perceivable hue can be
obtained by mixing three colors (e.g., a red, a green, and a blue) in appropriat ...