Colours of light can be added together to form a

variety of colours

How the eye sees colour

• The eye can only detect three colours of the visible light spectrum:– Red– Blue– Green

• These are known as the primary colours of light

• These colours then combine to form all other colours

Structure of the eye

Internal structure of the eye – notice that cone cells are located only at the back of the middle (macula) of the eye

Cones cells detect colour (RBG) while rod cells detect variation of shades of colour

Normal colour vision – cone cells help us see in colour

This is how a colour blind person sees “colours”

Dysfunctions of the rods cells of the eye

Partial function of the cones (red)

Additive Primary Colours

Magenta is a secondary colour – a

mixture of red and blue

Adding green creates two new

secondary colours:

Green + Red = Yellow

Green + Blue = Cyan

Adding all three primary colours

recreates white light

Combining Primary Additive Colours

The three secondary colours – magenta, yellow and cyan - are also complementary to the primary colour opposite to each.

Red is complementar

y to Cyan

Green is complementary to Magenta

Blue is complementar

y to Yellow

Combining colours of light – colour equations

Red + Green + Blue = White

R + G + B = WPrimary colours

Secondary colours Red + Blue = Magenta

R + B = M

Red + Green = Yellow

R + G = Y

Green + Blue = Cyan

G + B = C

Colour blindness tests

Everyone

Normal – 8

R/G = 3

Normal – 29

R/G = 70

Normal – 6

Deficiency - nothing

Normal – 45

Deficiency - nothing

Normal = nothing

CB - 45