color without hue. white, black, and all the grays between these two extremes.
additive color mixture
the creation of colors that occurs when lights of different colors are superimposed
a person who needs to mix a minimum of three wavelengths to match any other wavelength in the spectrum but mixes these wavelengths in different proportions from a trichromat
a loss of color vision caused by damage to the cortex
prolonged exposure to light in a specific part of the visible spectrum, which adapts receptors that fire to these wavelengths by selectively bleaching a specific visual pigment.
color with hue, such as blue, yellow, red, and green
a condition in which a person perceives no chromatic color. this can be caused by absent or malfunctioning cone receptors or by cortical damage.
the effect in which the perception of an object's hue remains constant even when the wavelength distribution of the illumination is changed. our perception of hue usually changes a little when the illumination changes, though not as much as we might expect from the change in wavelengths of light reaching the eye
people with this condition (sometimes incorrectly called color blindness) see fewer colors than people with normal color vision and need to mix fewer wavelengths to match any other wavelength in the spectrum
a procedure in which observers are asked to match the color in one field by mixing two or more lights in another field
low saturation in chromatic colors as would occur when white is added to a color. for example, pink is not as saturated as red.
a form of red-green color dichromatism caused by lack of the middle-wavelength cone pigment.
a person who has a form of color deficiency. can match any wavelengths in the spectrum by mixing two other wavelengths. deuteranopes, protanopes, and tritanopes.
the experience of a chromatic color such as red, green, yellow, or blue or combinations of these colors.
the border between two areas created by different light intensities in the two areas.
a display of colored dots used to test for the presence of color deficiency. the dots are colored so that people with normal (trichromatic) color vision can perceive numbers in the plate, but people with color deficiency cannot perceive these numbers or perceive different numbers than someone with trichromatic vision.
perception of reflectance. usually objects with high reflectance are perceived as white and objects with low reflectance are perceived as gray or black
the constancy of our perception of an object's lightness under different intensities of illumination.
the idea that an object's characteristic color influences our perception of that object's color
two lights that have different wavelength distributions but are perceptually identical
the situation in which two physically different stimuli are perceptually identical. in vision this refers to two lights with different wavelength distributions that are perceived as having the same color.
a person who is completely color-blind and therefore sees everything as black, white or shades of gray. can match any wavelength by adjusting the intensity of any other wavelength. generally only have one type of functioning receptors, usually rods.
the wavelength at which a dichromat perceives gray.
a neuron that has an excitatory response to wavelengths in one part of the spectrum and an inhibitory response to wavelengths in the other part of the spectrum
opponent-process theory of color vision
a theory originally proposed by Hering, which claimed that our perception of color is determined by the activity of two opponent mechanisms; a blue-yellow mechanism and a red-green mechanism. the responses to the two colors in each mechanism oppose each other an inhibitory response. in addition, this theory also includes a black-white mechanism, which is concerned with the perception of brightness.
the fuzzy border at the edge of a shadow
principle of univariance
absorption of a photon by a visual pigment molecule causes the same effect no matter what the wavelength
a form of visual agnosia in which the person can't recognize faces
a principle stating that two areas that reflect different amounts of light will look the same if the ratios of their intensities of their surroundings are the same
the percentage of light reflected from a surface
a plot showing the percentage of reflected from an object versus wavelengths
an edge between two areas where the reflectance of two surfaces changes.
the relative amount of whiteness in a chromatic color. the less whiteness a color contains, the more saturated it is.
when some wavelengths pass through visually transparent objects or substances and others do not. associated with the perception of chromatic color.
when an object reflects some wavelengths of the spectrum more than others.
simultaneous color contrast
the effect that occurs when surrounding one color with another changes the appearance of surrounded color.
subtractive color mixture
the creation of colors that occurs when paints of different colors are mixed together
a person with normal color vision. can match any wavelength in the spectrum by mixing three other wavelengths in various proportions
trichromatic theory of color vision
a theory proposing that our perception of color is determined by the ratio of activity in three receptor mechanisms with different spectral sensitivities.
a form of dichromatism thought to be caused by a lack of the short-wavelength cone pigment.
a person who has dichromatic vision in one eye and trichromatic vision in the other eye. people with this condition (rare) have been tested to determine what colors a dichromat perceives by asking them to compare the perceptions they experience with their dichromatic eye and their trichromatic eye
young-helmholtz theory of color vision
trichromatic theory of color visionth
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