colour

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col·or

(kŭl'ŏr)
1. That aspect of the appearance of objects and light sources that may be specified as to hue, lightness (brightness), and saturation.
2. That portion of the visible (370-760 nm) electromagnetic spectrum specified as to wavelength, luminosity, and purity.
Synonym(s): colour.
[L.]

colour 

An aspect of visual perception, characterized by the attributes of hue, brightness and saturation, and resulting from stimulation of the retina by visible photopic light levels. Note: also spelled color.
achromatic colour A visual sensation resulting from a stimulus having brightness, but devoid of hue or saturation, e.g. white, grey.
colour agnosia See agnosia.
colour blindness 
See colour blindness.
complementary colour One of a pair of colours which, when mixed additively, produce white or grey (that is to say an achromatic sensation). Examples: green is the complementary colour of red-purple and yellow is the complementary colour of blue. See chromaticity diagram.
confusion colour's Colours that are confused by a dichromat. The colours confused by a deuteranope, a protanope and a tritanope are not the same. For example, the deuteranope will confuse reds, greens and greys, whereas the protanope will confuse reds, oranges, blue-greens and greys. See pseudoisochromatic plates.
colour constancy See colour constancy.
colour contrast See colour contrast.
defective colour vision Marked departure of an individual's colour vision aptitude from that of a normal observer. This is indicated by various tests, e.g. anomaloscope, pseudoisochromatic plates, Farnsworth test. The following types of defective colour vision are usually recognized: anomalous trichromatic vision or anomalous trichromatism; dichromatic vision or dichromatism; monochromatic vision or monochromatism (total colour blindness), anomaly of vision in which there is perception of luminance but not of colour. Both anomalous trichromatism and dichromatism occur in three distinct forms called respectively protanomalous vision and protanopia, deuteranomalous vision and deuteranopia, tritanomalous vision and tritanopia.The causes of defective colour vision may be an impairment of a cone pigment or a reduced number of cone cells. The majority of cases of defective colour vision are inherited and thus bilateral. Acquired defects are rare, mostly tritanopic and appear in one eye or are asymmetric, and affect males and females equally. They may be due to glaucoma, retinal or optic nerve disease, drug or chemical toxicity, diabetes, retinitis pigmentosa, etc. Hence it is essential to test colour vision under monocular conditions. The inherited type occurs as a sex-linked disorder in which the defective gene is on the X chromosome. Since men have only one X chromosome while women have two, sex-linked disorders (most being X-linked recessive) affect mainly males who inherit the genetic defect from their mother. Inherited tritanopia and tritanomaly are usually autosomal dominant. For women to show the defect, both of their X chromosomes have to carry the defective gene, a rare occurrence. Defective colour vision occurs in about 8% of the male population and 0.5% of the female population. Syn. daltonism. See achromatopsia; anomaloscope; deuteranomaly; deuteranopia; inheritance; ChromaGen lens; X-Chrom lens; monochromat; visual pigment; protanomaly; protanopia; Kollner's rule; colour vision test; tritanomaly; tritanopia.
colour fringes Coloured edges around images formed by a lens or an optical system which is not corrected for chromatic aberration.
fundamental colour's See primary colours.
colour induction See colour induction.
colour matching Action of making a colour appear the same as a given colour.
metameric colour Spectrally different radiations that produce the same colour under the same viewing conditions. Note: The corresponding property is called metamerism. Syn. metamers (CIE).
colour mixture The production of a colour by mixing two or more lights of different colours (additive colour mixture) or two or more pigments (subtractive colour mixture). See complementary colour; primary colours.
Munsell colour See Munsell colour system.
non-spectral colour Any colour that does not exist as a single wavelength. Example: purple, which is a mixture of blue and red radiations. See purple.
primary colour's Any sets of three colours such as, for example, red, green and blue, which, by additive colour mixture of the stimuli in varying proportions, can produce any colour sensation. Syn. fundamental colours.
spectral colour's The colours produced by the various radiations of the visible spectrum. See light.
colour space See space, colour.
colour stereoscopy 
See chromostereopsis.
surface colour Colour perceived as belonging to a surface of an object which is not self-luminous.
colour temperature The temperature of the surface of an ideal black body which emits radiations of the same chromaticity as that from the source being specified. As the temperature increases, the amount of radiations increases and the source changes colour from red through to white to blue-white. Unit: Kelvin (symbol: K).
colour triangle See chromaticity diagram.
colour vision See colour vision.
colour vision, aetiology of See defective colour vision.
References in periodicals archive ?
Clonbrin Darkie, who was due to do battle with his near-four-year-old litter-brother Clonbrin Owl in the Pre-Festival Veterans, is also off-colour and has been scratched.
She was just off-colour and was already showing improvement on Monday morning.
He was genuinely flat that night and was off-colour afterwards, but his well over that now, and I couldn't be happier with him after Monday's race," explained Andreas.
JOHN MULLINS has withdrawn two of his intended nine-strong team from today's Nottingham meeting-Illinois Icon missing the final of the Hucknall Racing Puppy Cup and Crucked Road the final of the Steve Charlesworth Trophy, both off-colour.
ROMFORD trainer Chris Duggan's kennels have been hit by sickness and all six of his intended runners at the Essex track last night were withdrawn, three actually off-colour and the other three for precautionary reasons.
The vet checked her over, and confirmed she was off-colour, and couldn't run.
Haydn Jones had supplied Norton with one of his Bath winners and Miss Flirtatious's victory, the 11th of the year for the trainer, was further confirmation that the Pontypridd stable is back in good health after being off-colour in recent seasons.
EL MITO, who was withdrawn apparently off-colour from the William Hill Derby on Saturday morning, bizarrely ran in an A1 contest at Walthamstow on the night, coming home fifth behind None So Blue.