We are used to thinking of red, yellow and blue as the three primary colours. Paints of these colours can be mixed to create the other colours of the spectrum. But coloured lights work in a different way. The primary colours of light are red, green and blue. When lights are mixed in pairs, they create the secondary colours of magenta, cyan and yellow. When all three colours are mixed together in equal amounts, white light is the result.
The animation above left shows subtractive mixing. The background is white, meaning that the red, green and blue pixels all emit maximum light, and our animation subtracts from this white background. In the top circle, the red and green pixels are kept at maximum, while the blue pixels vary from zero to maximum and back again, so that the colour at the top varies from yellow (=red+green) to white (=red+green+blue) and back again.
In the circle at right, the green and blue pixels are kept at maximum while the red pixels vary, so the colour at right goes from cyan (=green+blue) to white and back again. Where the yellow and cyan overlap, we see the subtractive mixture of yellow and cyan. In other words, we see white from which yellow has subtracted blue and cyan has subtracted red. This leaves green, i.e. the subtractive mix of yellow and cyan = white–blue–red = green.
In the left circle, the red and blue pixels are kept at maximum, while the green pixels vary, so that the colour at left varies from magenta (red+blue) to white and back again. Where the yellow and magenta overlap, we see the subtractive mixture of yellow and magenta. In other words, we see white from which the yellow filter has subtracted blue and the magenta filter has subtracted green. This leaves red, i.e. the subtractive mix of yellow and magenta = white–blue–green = red.
Where the magenta and cyan overlap, we see the subtractive mixture of magenta and cyan. In other words, we see white from which the magenta filter has subtracted green and the cyan filter has subtracted red. This leaves green, i.e. the subtractive mix of magenta and cyan = white–green–red = blue.
Finally, where yellow, magenta and cyan overlap in the centre, we see the subtractive mixture of yellow, magenta and cyan. In other words, we see white from which the yellow filter has subtracted blue, the magenta filter has subtracted green and the cyan filter has subtracted red. This leaves nothing: the subtractive mix of yellow, magenta and cyan = white–blue–green–red = black.
Picture Credit : Google
