| Helmholtz theory of colour vision | A theory that there are three colour-perceiving elements in the retina: red, green, and blue. Perception of other colours arises from the combined stimulation of these elements; deficiency or absence of any one of these elements results in inability to perceive that colour and a misperception of any other colour of which it forms a part. Synonym: Helmholtz theory of colour vision. (05 Mar 2000) |
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| saturated colour | A colour containing a minimum amount of whiteness. (05 Mar 2000) |
| Hering's theory of colour vision | That there are three opponent visual processes: blue-yellow, red-green, and white-black. (05 Mar 2000) |
| pure colour | A visual sensation produced by light of a specific wavelength. (05 Mar 2000) |
| simple colour | The three colour's of the retinal cone pigments (red, green, blue) that may be combined to match any hue. Synonym: simple colour. (05 Mar 2000) |
| structural colour | A colour created by an optical effect (e.g., via interference, refraction, or diffraction). Many naturally occurring blues fall in this class. Compare: natural pigment. Synonym: schemochromes. (05 Mar 2000) |
| Doppler colour flow | A computer-generated colour image produced by Doppler ultrasonography in which different directions of flow are represented by different hues. This technique is typically used to examine blood flow when evaluating heart disease. Where obstructions (for instance, arterial plaques) exist, blood flow will alter according to the principles of fluid mechanics. Eddies and reversals are readily apparent on the colour image. See: Doppler ultrasonography. (05 Mar 2000) |
| incidental colour | An obsolete term for a colour impression that remains after removal of the source. See: afterimage. (05 Mar 2000) |
| intrinsic colour | <dentistry> The addition of colour pigment within the material of a dental prosthesis. (05 Mar 2000) |
| opponent colour | Pairs of colour that share colour channels in the retina (red-green, blue-yellow, black-white). (05 Mar 2000) |
| echocardiography, doppler, colour | Echocardiography applying the doppler effect, with the superposition of flow information as colours on a gray scale in a real-time image. (12 Dec 1998) |
| tone colour | The distinguishing quality of a sound, by which one may determine its source. Synonym: tone colour. Origin: Fr. (05 Mar 2000) |
| extrinsic colour | Colour applied to the external surface of a dental prosthesis. (05 Mar 2000) |
| eye colour | Colour of the iris. (12 Dec 1998) |
| Young-Helmholtz theory of colour vision | A theory that there are three colour-perceiving elements in the retina: red, green, and blue. Perception of other colours arises from the combined stimulation of these elements; deficiency or absence of any one of these elements results in inability to perceive that colour and a misperception of any other colour of which it forms a part. Synonym: Helmholtz theory of colour vision. (05 Mar 2000) |