- Additive colour refers to the method used to mix wavelengths of light.
- Colour models can produce vast numbers of colours simply by adding red, green and blue lights together in different proportions.
- Subtractive colour refers the method used when mixing pigments such as dyes, inks and paints.
- An additive approach to colour is commonly used to control the appearance of colours on the digital screens of TVs, computers and phones.
- The RGB, HSB and Spectral colour models use an additive approach to colour.
- A colour model can be thought of as a colour theory, whilst additive colour and subtractive colour refer to how the colour model works in practice.
About additive colour and the RGB colour model
The RGB colour model used by TV, computer and phone screens involves additive colour mixing. The RGB colour model produces all the colours seen by an observer simply by combining the light emitted by arrays of red, green and blue pixels (picture elements) in different proportions.
- RGB colour is an additive colour model that combines wavelengths of light corresponding with red, green and blue primary colours to produce all other colours.
- Red, green and blue are called additive primary colours in an RGB colour model because just these three component colours can produce any other colour if mixed in the right proportion.
- 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 in equal amounts, they produce white.
- A fully saturated colour is produced by a single wavelength (or narrow band of wavelengths) of light.
- When any two fully saturated additive primary colours are combined, they produce a secondary colour: yellow, cyan or magenta.
- Some implementations of RGB colour models can produce millions of colours by varying the intensity of each of the three primary colours.
- The additive RGB colour model cannot be used for mixing pigments such as paints, inks, dyes or powders.