Chapter 5 Flashcards
Visible spectrum
The portion of the electromagnetic spectrum in the range of about 400 to about 700 nm; within this range, people with normal vision perceive differences in wavelength as differences in color.
Color vision
The ability to see differences between lights of different wavelengths
Spectral power distribution
The intensity of a light at each wavelength in the visible spectrum
Heterochromatic light
Light that consists of more than one wavelength
Monochromatic light
Light that consists of only one wavelength
Achromatic light
Light containing wavelengths from across the visible spectrum, with no really dominant wavelengths; perceived more or less colorless
Spectral reflectance
The proportion of light that a surface reflects at each wavelength
Hue
The quality usually referred to as “color” that is, blue, green, yellow, red, and so on; the perceptual characteristic most closely associated with the wavelength of light
Saturation
The vividness of a hue
Color circle
The 2-D depiction in which hue varies around the circumference and saturation varies along any radius
Color Solid
A 3-D depiction in which hue varies around the circumference, saturation varies along any radius, and brightness varies vertically
Subtractive color mixture
A mixture of different-colored substances; called “subtractive” because the light reflected from he mixture has certain wavelengths subtracted by each substance in the mixture
Additive color mixture
A mixture of different-colored lights; called “additive” because the perceived color of the mixture is the result of adding together all the wavelengths in all the lights in the mixture
Complementary colors
Pairs of colors that when combined in equal proportion, are perceived as a shade of gray
Primary colors
Any three colors that can be combined in different proportions to produce a range of colors
Meta ears
Any two stimuli that are physically different but are perceived as identical
Spectral sensitivity function
The probability that a cones photopigment will absorb a photon of light of any given wavelength
Principle of univariance
With regard to cones, the principle that absorption of a photon of light results in the same response regardless of the wavelength of the light.
Hue cancellations
An experimental technique in which the person cancels out any perception of a particular color in a test light by adding light of the complementary color
Photopigment bleaching
A photopigment molecule’s loss of ability to absorb light for a period after undergoing photoisomerization
Chromatic adaption
A kind of photopigment bleaching that results from exposure to relatively intense light consisting of a narrow range of wavelengths
Color constancy
The tendency to see a surface as having the same color under illumination by lights with very different spectral power distributions
Lightness consistency
The tendency to see a surface as having the same lightness under illumination by very different amounts of light
Monochromacy
A condition in which a person has only rods or has only rods and one type of cone; in either case, the person is totally color-blind, perceiving everything in shades of gray
Rod monochromacy
A condition in which a person has rods only, with no cones
Cone monochromacy
A condition in which a person has rods and only one type of cone
Dichromacy
A condition in which s person has only two types of cones, instead of the normal three; in all such cases, the person has a limited form of color vision but cannot discriminate as many colors as a person with all three cone types
Protanopia
A condition in which a person has M-cones and S-cones but lacks L-cones
Deuteranopia
A condition in which a person has L-cones and S-cones but lacks M-cones
Trianopia
A condition in which a person has L cones and M cones but lacks S cones
Ichihara color vision test
A test using configurations of multicolored disks with embedded symbols; the symbols can be seen by people with normal vision but not by people with particular color vision deficiencies
Achromatopsia
Loss of color vision caused by brain damage
