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Primary Colours

Maxwell showed how to mix colours.

Maxwell did more than explain the nature of pure colours. He also described how colours could be mixed.

Maxwell showed that a combination of three primary colours could make every other colour.

Any three colours can be used. However sometimes you need to subtract a primary colour. Since subtracting colours is not really possible, how large a range of colours you can actually make depends on which three colours you start with.

Maxwell's discovery allowed him to invent colour photography. Today we still use three primary colours to make colour photographs - as well as colours on television and computers, or in books and magazines.

Some scientists had suggested the idea of primary colours before Maxwell. In fact Thomas Young had suggested that we perceive colours using three different colour receptors in our eyes.

This idea is correct! By combining the information from three different kinds of cell—one that responds to red light, one to green light and one to blue light—our brains can reconstruct the colour we are seeing.

However perception of colour is more complex than this. It is affected by many factors including the amount of light we see, and the way the object is moving.

magnifyJames Clerk Maxwell

magnifyThomas Young

Optical illusion
magnifyOptical illusion
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