Additive colour

Additive colour is a method of mixing two or more wavelengths of light to produce other colours.

About additive colour
  • Additive colour is the method used to mix wavelengths of light, whilst subtractive colour is the method used to mix dyes, inks and paints.
  • An additive approach to colour is used for the emission of light by the screens of televisions, computers and mobile phones.
  • An additive approach to colour is used for the projection of light by digital projectors which is then reflected off a white surface towards an observer.
  • A colour model can be thought of as a theory of colour whilst additive colour or subtractive colour usually refers to the method used to apply it in practice.
Additive colour and the RGB colour model

The RGB colour model used by TV’s, computers and mobile phones involves additive colour mixing, producing all the colours seen by an observer by combining light emitted by tiny red, green and blue light sources embedded in the screen.

  • RGB colour is an additive colour model that combines wavelengths of light corresponding with red, green and blue primary colours to produce other colours.
  • Red, green and blue are called additive primary colours in an RGB colour model because they can be added together to produce all other colours.
  • RGB colour uses three light sources or beams. Each is called a component of the resulting colour.
  • Different colours are produced by varying the intensity of the component colours between fully off and fully on.
  • When fully saturated red, green and blue primary colours are combined, they produce white.
  • When any two fully saturated additive primaries are combined, they produce a secondary colour: yellow, cyan or magenta.
  • Some RGB colour models can produce over 16 million colours by varying the proportion of each of the three primary colours.
  • The additive RGB colour model cannot be used for mixing different colours of pigments, paints, inks, dyes or powders.