Seeing in colour

About seeing in colour
  • When an observer considers the colour of something, they might refer to:
    • Spectral colours and use names commonly associated with rainbows (ROYGBV).
    • A specific colour model such as RGB, CMYK or HSB.
    • A family of colours such as warm or cool colours.
    • Tints or shades of colours.
    • A palette of colours they have selected or are working with.
    • A broader vocabulary of colour names, such as dark red, vermilion, golden yellow, lemon yellow, pale yellow, greenish-yellow, chartreuse, leaf green, or light green.

Wavelengths of light & colour vision

About wavelengths of light and colour vision

There is a clear difference between the wavelengths of light that make up the visible spectrum and how the human eye converts the information it receives about wavelength into the perception of colour.

  • The human eye, and so visual perception, is tuned to the visible spectrum and so to spectral colours between red and violet.
  • It is the sensitivity of the eye to this small part of the electromagnetic spectrum that results in the perception of colour.
  • Photosensitive cone cells embedded in the retina of each eye respond to wavelengths of light corresponding with spectral colours.
  • Explained in simple terms, cone cells distinguish between different colours by determining how much red, green and blue are present when stimulated by their corresponding wavelengths.
  • The system used by the human eye to distinguish colours is called trichromacy or trichromatic colour vision.
  • The spread of wavelengths that the spectral colour model is concerned with is well suited to a linear arrangement with the shortest at one and the longest at the other.
  • The way the human eye determines colour from the presence of three primary colours (red, green and blue) lends itself to a circular, wheel-like arrangement.
  • The RGB color model used in digital displays and imaging devices is based on the trichromatic nature of human vision.