Saturation

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

  • Saturation (colour saturation) refers to the perceived difference between one colour and another in terms of purity.
  • A saturated colour is a pure, 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.
    • Bands of colour are composed of a continuous range of wavelengths.
    • Spectral colours are composed of a single wavelength of light (or a narrow band of wavelengths).
    • Non-spectral colours are produced by additive mixtures of wavelengths of light 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 difference between the RGB and HSB colour models is limited to 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 intuitive way to select and adjust colours when using applications such as Adobe Creative Cloud for design, photography or web development.
  • The HSB colour model is popular because it provides an intuitive way to select and adjust colours in software applications used for graphic design, web development and photography.
  • Whilst RGB relies on adjusting the amount of red, green and blue needed to produce other colours the HSB colour model relies on adjusting hue, saturation and brightness.
  • Both the RGB and 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 perceived difference between one colour and another and is usually described by using names such as red, yellow, green or blue.
    • Hue can be measured as a location on an HSB colour wheel and expressed as a degree between 00 and 3600.
  • Saturation refers to the perceived difference between one colour and another in terms of vividness.
    • Saturation 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 difference between the way a colour appears to an observer in well-lit conditions compared with its subdued appearance when in shadow or when poorly illuminated.
    • Brightness can be measured as a percentage from 100% to 0%. As the brightness of a fully saturated hue decreases it appears progressively darker and achromatic.