Visual perception of colours

There are three types of colour receptors in our eye: red, green and blue.

But how do we see the amazing kaleidoscope of other colours that make up our world?

Colm Kelleher explains how humans can see everything from auburn to aquamarine.

“see video”

07 Colour visualisation 05

This is just the beginning of colour theory. To give you a glimpse of how complex it gets, consider this:

Once visual information arrives in our brain, it goes through a whole battery of subconscious processes before we become consciously aware of what we are seeing. These processes allow us to discard huge amounts of extraneous information, build a coherent 3D model of our environment, detect edges and object forms, and make deductions about lighting. In general, this is incredibly useful as it allows us to go about our lives without needing to consciously try and figure out where the edges of a table are, or how high up in a building we are if we look out the window.

However, as designers working with colour, there are some important aspects of this subconscious processing we need to understand, which basically all relate to the fact that the same colour can look very different depending on its context. For example, placing two contrasting colours next to each other will make them both appear more “colourful”

When a colour is juxtaposed with other colours, we perceive it as a different colour. For example, most people will say the small square on the left is orange, whereas the one on the right is brown:

07 Colour visualisation 01

Actually, the squares are exactly the same colour!!!

07 Colour visualisation 04

It gets worse, because the brain projects abstract things it knows about the natural world onto your perception of colour. For example, we know intuitively that shadows artificially darken colours, so our brains automatically account for this in our perception of those colours. (It’s called “colour constancy.”) For example, you know that the dark and light colours on this hot air balloon are “the same:”

07 Colour visualisation 02

But it also results in optical illusions so powerful that even when you know the trick you still can’t see it correctly. Like this: Which square is darker: A or B?

07 Colour visualisation 03

In fact A and B are the same colour (#787878), but you can’t see it even when you know this. To prove it to myself I had to open this picture in an image editor and actually move one square over another to see it was the same.


Colour in the making, Black dot publishing, UK,2013


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