Colour illusions

For example: Red + Green = Yellow

This is a different result from that obtained by mixing two coloured lights. Here the colour produced is brighter than the single colours because the light intensities are added together:

Red + Green = Yellow

Colour fusion

We can demonstrate the effect of mixing colours by using spinning discs.

The paints on the disc reflect coloured light to your eyes. When they spin the colours move too quickly to be seen separately. The result is that we see a fusion mixture of the colours.

The brightness of the colours which are produced is an average of the brightness of the painted sections.