Complementary colours

In the context of a discussion of light, complementary colours are pairs of colours that, when mixed together produce white and when placed next to each other create the strongest contrast.

About complementary colours and colour wheels
  • Complementary colours are always opposite one another on a colour wheel.
  • The complementary colour of a primary colour is always a secondary colour on a colour wheel.
  • The pairs of primary and secondary colours that produce complementary colours depend on the colour model:
  • Whilst the secondary colours in a subtractive RYB colour wheel are green, purple and orange, mixing pigments (eg. paints or inks) is a complicated business.
  • Combinations of two complementary colours of light at full intensity produces white.
Complementary colours and the the RGB colour model
  • When using the RGB colour model, the primary/secondary pairs of complementary colours are red-cyan, green-magenta and blue-yellow.
  • Combining the wavelengths corresponding with all three RGB primary colours produces the impression of white for a human observer.
  • When working with the RGB colour model the secondary colour that pairs with any primary colour is produced by mixing the other two primaries together.

https://en.wikipedia.org/wiki/Complementary_colors