| Colour Science It rejected the idea of there being three fixed colours (Red Yellow Blue). All the colours that could be produced by combining any three colours in different ways is called the gamut of those three colours. In additive colouring, light of different wavelengths is ‘mixed’ to yield light of one combined colour. In subtractive colouring, a colour is rendered by passing white light through a medium that absorbs or takes away, specific wavelengths of light, leaving the rest to render a particular colour. |
Colour is a type of information our eyes receive and process based on electromagnetic radiation.
- An object has a colour based on which frequencies of visible-light radiation it absorbs, reflects, and/or scatters.
- In the human eye, the rod and the cone cells receive information in the light that strikes the eye: the rod cells record brightness while the cone cells record the wavelengths, which the human brain interprets as colour.
- Human beings have three types of cone cells. Each type is sensitive to light of a different wavelength, and they work together to input colour information to the brain.
- The possession of three types of cone cells is why humans are called trichromats.
- Many birds and reptiles, on the other hand, are tetrachromats (four types of cone cells).
- Similarly, while human vision is restricted to wavelengths from 400 nm to 700 nm, honeybees can ‘see’ ultraviolet light and mosquitoes and some beetles can access information in some wavelengths of infrared radiation.
- Properties of colour-
- In 2002, a Technical committee of the International Commission on Illumination specified the definition of hue to be the degree to which a given (perceived) colour can be said to be similar to or different from perceived red, orange, yellow, green, blue or violet.
- Brightness is related to an object’s luminance. The luminance is the power emitted by a source of light per unit area, weighted by wavelength; the eye’s subjective perception of this power in some direction is inferred as the source’s brightness.
- Lightness refers to the extent to which a coloured object appears light compared to a white-coloured object that is well-lit.
- The chromaticity, or chromatic intensity, has to do with the human perception of colour and depends on the colour’s quality irrespective of how well it is lit.
Dig Deeper: Which space telescopes are used by India or the World to observe celestial wonders hidden in radio waves, X-rays, gamma rays and ultraviolet light?
