Mixing Pixels

Take a single drop of water on your fingertip and flick it on your computer screen, on the colours below:

Take a close look at those little drops.

They show how your computer makes colours. Look carefully at the drops on the top row - you should see the combinations red/black, green/black, blue/black.

Your computer uses mixtures of red, green and blue to make all the other colours. So the only way to make red is to turn the red pixels on and the others off. The turned-off blue and green pixels form a black background.

Blue and green work the same way.

Additive Colours

Red, green and blue are called additive primaries, because you add some of each to create different colours.

Now, look at the droplets on the bottom row of colours. See how they're different from the top row?

The yellow, cyan (light blue) and magenta (purple) colours are made by combining red, green and blue pixels in pairs. Use your water-drop magnifier to figure out which two primary colours make up each one, then check the answer.

Subtractive Colours

Yellow, cyan and magenta are called subtractive primaries since they are made by subtracting just one of red, green and blue from a white background. They are the primary colours used in printing, painting and crayons.

But aren't the primary colours red, yellow and blue?