colour

colour

(US), color

1. 

a. an attribute of things that results from the light they reflect, transmit, or emit in so far as this light causes a visual sensation that depends on its wavelengths

b. the aspect of visual perception by which an observer recognizes this attribute

c. the quality of the light producing this aspect of visual perception

d. (as modifier): colour vision

2. 

a. a colour, such as red or green, that possesses hue, as opposed to achromatic colours such as white or black

b. (as modifier): a colour television

3. 

a. the skin complexion of a person, esp as determined by his race

b. (as modifier): colour prejudice

4. the use of all the hues in painting as distinct from composition, form, and light and shade

5. the distinctive tone of a musical sound; timbre

6. Physics one of three characteristics of quarks, designated red, blue, or green, but having no relationship with the physical sensation

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

color (perceived)

That attribute of visual perception that can be described by names such as yellow, red, blue, etc., or some combination of such names. (of an object) A characteristic of the appearance of an object, surface, etc., distinct from its form, gloss, shape, size, or position; depends on the spectral composition of the incident light, on the spectral reflectance or transmittance of the object, and on the spectral response of the observer.

McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

colour

(graphics)

(US "color") Colours are usually represented as RGB triples in a digital image because this corresponds most closely to the electronic signals needed to drive a CRT. Several equivalent systems ("colour models") exist, e.g. HSB. A colour image may be stored as three separate images, one for each of red, green, and blue, or each pixel may encode the colour using separate bit-fields for each colour component, or each pixel may store a logical colour number which is looked up in a hardware colour palette to find the colour to display.

Printers may use the CMYK or Pantone representations of colours as well as RGB.

This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)