Overlapping Beams of Cyan, Magenta and Yellow




To find out more about the diagram above . . . . read on!

Yellow, Cyan and Magenta Lights Projected onto a Dark Surface

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!

  1. Name three colours and their corresponding wavelengths of light that when mixed together in equal proportions make white?
  2. Why do inks and pigments corresponding with the three CMY primary colours produce a dark brown or black?
  3. Why do overlapping wavelengths of light corresponding with cyan, magenta and yellow make white?
  4. What is an RGB colourwheel?
  5. What is the difference between spectral colour and RGB colour?

About the Diagram

Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

This diagram shows the effect of projecting lights producing the RGB secondary colours (cyan, magenta and yellow) onto a neutral coloured surface.

  • Imagine that the three circles of colour (cyan, magenta and yellow) are produced by torches shining beams of light so they overlap one another.
  • In the RGB colour model, cyan, magenta and yellow are secondary colours. Notice what colours are produced where they overlap – it’s the three primary colours!
  • Overlapping pairs of primary colours produce secondary colours.
  • Overlapping pairs of secondary colours produce primary colours.
  • Remember that the area where all three primary colours or all three secondary colours overlap is white.

About the RGB colour model

  • RGB colour is an additive colour model that combines wavelengths of light corresponding with the red, green and blue primary colours to produce other colours.
  • RGB colour is called a model because it is a method that can be followed to produce any colour from a combination of red, green and blue light.
  • Red, green and blue are called additive primary colours in an RGB colour model because they can be added together to produce any other colour.
  • When mixing light, each RGB primary colour 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 any two fully saturated RGB primaries are combined they produce a secondary colour: yellow, cyan or magenta.
  • When fully saturated red, green and blue primary colours are all combined together they produce white.
  • Some RGB colour models can produce over 16 million colours by varying the proportion and intensity of each of the three component primary colours.
  • The additive RGB colour model cannot be used for mixing different colours of pigments, paints, inks, dyes or powders. To understand these colourants find out about subtractive colour.
  •  The RGB colour model does not define the precise wavelength or band of wavelengths for the primary colours red, green and blue.
  • When the exact composition of primary colours are defined, the colour model then becomes an absolute colour space.

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Some Key Terms

Move to the next level! Check out the following terms.

Colour wheel

A colour wheel is a diagram based on a circle divided into segments. The minimum number of segments is three ...
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Primary colour

Primary colours are a set of colours from which others can be produced by mixing (pigments, dyes etc.) or overlapping ...
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Colour model

A colour model is a mathematical system used to describe colours using a set of numeric values. A colour model ...
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White light

White light is the name given to visible light that contains all wavelengths of the visible spectrum at equal intensities ...
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