Saturation refers to the perceived difference between one colour and another in terms of its purity and vividness. The hue of a vivid colour appears to be at full strength rather than looking insipid or washed out.

  • A saturated colour is a unique spectral colour produced by a single wavelength (or a narrow band of wavelengths) of light.
  • A fully saturated colour (100%) is the purest version of a hue.
  • Unsaturated colours appear dull and washed out until their hue disappears leaving only monochromatic grey tones.
About saturation & wavelength
  • A colour appears saturated when it is produced by a single (or narrow range) of wavelengths.
  • A colour produced by a single wavelength of light is often referred to as pure spectral colour.
  • Unsaturated colours appear washed out because they contain a broader range of wavelengths.
  • Saturation is related to light complexity.
  • Light complexity refers to the arrangement of wavelengths of light used to produce a colour.
    • Spectral colours are very simple in the sense that they are composed of a single wavelength of light.
    • Bands of colour are relatively simple because they are composed of a continuous range of wavelengths.
    • Non-spectral colours may combine any number of wavelengths from different areas of the spectrum and so are the most complex.
  • In real life, colours are produced by very complex mixtures of wavelengths. The greater number and spread of wavelengths across the visible spectrum, the lower the saturation of a colour.
About saturation and colour models
About the HSB colour model

The HSB colour model is an additive colour model used to mix light. Subtractive colour models are used to mix pigments and inks.

  • The only difference between HSB and RGB colour models is the way colours are represented in terms of colour notation and dealt with in software and apps.
  • Both the HSB and RGB colour models deal with how to mix red, green and blue light to produce other colours.
  • HSB is popular because it provides an easy way to select and adjust colours when using applications such as Adobe Creative Cloud for design, photography or web development.
  • The HSB colour model can be used to describe any colour on a TV, computer or phone.

In the HSB colour model:

  • Hue refers to the property of light by which the colour of an object is classified as similar to red, yellow, green or blue and is measured as a location on the standard colour wheel and expressed in degrees between 0 and 360.
  • Saturation refers to the intensity of colour and is measured between a fully saturated colour (100%) and an unsaturated colour that appears dull and washed out until all colour disappears leaving only a monochromatic grey tone (0%).
    • A fully saturated colour is produced by a single wavelength or a narrow band of wavelengths.
    • On HSB colour wheels, saturation is usually shown to increase from the centre to the circumference.
  • Brightness (colour brightness) refers to the perceived amount of light emitted by a colour and is measured as a percentage from 100% (fully lit) to 0% (no light emitted).
    • As the brightness of a fully saturated hue decreases it appears progressively darker.