VL Lecture: Colour Theory

A couple of weeks ago I attended a series (two) of lectures on Colour Theory, and they were easily the most interesting lectures I have been to so far, along with Mike's lecture on the history of animation. Within two hours we had covered Colour Theory in depth, and learned about how we perceive different colours as well as the different dimensions of colour and colour modes.

So how do we know that this apple is red?

We know that this apple is red because of how our eyes perceive colour. The eye is made up of two receptors; rods and cones. The rods are responsible for conveying black, white and grey tones, where as the cones deal with colour, but we can only perceive these colours when light is present. White light is made up of a whole spectrum of colours, and we can perceive these different colours when the different cones in our eyes are stimulated, as there are three different cones that are sensitive to different colours (Red, Green and Blue-Violet). For instance, if the both the red and the green cones are simultaneously stimulated we will perceive the colour yellow. Due to this, the light in which we see colour effects our perception of colour.

But is this apple really red?

We can safely say it IS, because at the moment it is the "reddest" thing we can see. But if we compare this apple to a pure red, it then appears much darker. Like so.

Comparison of Supposed "Red" Apple to Red

This is because there are many different hues, tones and saturations of each colour, other wise known as chromatic values. This is a number that is assigned to each colour in the colour spectrum, so we can distinguish between different tones of colours. We can use chromatic values to print or select the exact same colour as someone else as it is a globally agreed system of labelling colours, but this doesn't mean that we are going to perceive this colour in the same way. So technically speaking "Red" is a concept that doesn't exist.