Magenta is not a ‘real’ colour and other mysteries

I have never paid that much attention to colour theory, I know how to mix red, green and blue programatically in various languages and environments to get what I want and that’s about it.

But an article I have just read on how colour really works is fascinating.

The first thing that made me sit up and think is the observation that magenta is not a ‘real’ colour – in the sense that there is no wavelength of light that corresponds to magenta. (I suppose I have always thought of it as a ‘light violet’, but it’s not really.)
magenta square
Of course the colour is “real” but its reality is not based on simple physics – that square is simply made up from (if you are using an old fashioned CRT monitor) equally bright blue and red dots. The “colour” is manufactured in your brain. It is what is known as an “extra spectral” colour and of course their are many of these we see in daily life: just think of brown.

The way the brain handles colour is fascinating – this optical illusion – which I have seen before but which continue to amaze me – is a great example. Squares A and B could not possibly be the same colour – but, in fact, they are: your brain automatically corrects for the shadow.

Chess squares

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