Colour is so important to us. One of the reasons humans have evolved into such a successful species is our ability to distinguish lots of different colours. Many animals cannot see red tones, so in a jungle, a tiger doesn’t look orange to it’s prey, it looks browny-green, thus easily blending into the landscape, but to humans, we see the colour and can more quickly act to avoid being lunch.
Inside our eyes we have around 120 million rods and 6-7 million cones. The rods are sensitive to light and dark, seeing colours in the black, white,grey spectrum , the cones to colour, which pick up either red, blue or green colours.
1 in 10 men have some colour deficit and 1 in 200 women have the same problems picking up the differences in colour.
How someone sees colour who has full colour vision
There are different sorts of colour blindness
Protanopia – the complete absence of the ability to pick up red
Deuteraonopia – the green retinal photoreceptors are absent, moderately affecting red-green hue discrimination..
Tritanopia is a very rare color vision disturbance in which there are only two cone pigments present and a total absence of blue retinal receptors
If you want to see more examples of what people see (really important if you’re designing something) this is a useful link.
Pics courtesy: Wikipedia