[Week I] Hue, Third Entry - The Science of Hue

How do we Perceive Hue?

What exactly changes within our brains that makes one colour have a different hue from another? In our eyes we have many specialised cells that help us see, but it's the Ganglion cells that help us differentiate the hue of one colour from another.

Ganglion Cells

You don't need to fully understand every aspect of these cells, but you should notice that there are in fact two different types of Ganglion cells. Red-green ones and Blue-yellow ones. Another thing to notice that in the image above, we have a large Red-green cell being shown on the left. This cell would determine how much red or green is in the light we see by comparing the response from the red area or green area. More response from the red area, the more red there is in the light we see.

How do We Change Hue?

Why do the cells respond different to lights anyway? Colour, and thus hue, comes from the spectrum of light. By varying the wavelengths of light, we can force our eyes to see things differently. In computer graphics we must know how to replicate specific colours, and we can do this by having a defined colour model.

HSV Colour Space

By using an abstract mathematical model, we can refer back to colours in a computer by using specific numbers. We can tell a computer these numbers, and have it reproduce a colour by sending a signal to our monitors of what wavelengths the light should have.

How does Nature Change Hue?

We can control the wavelengths of light through technology, but then how does a chameleon change the hue of its colour? The chameleons have their own specialised cells called Chromatophores. 

Similar to the Ganglion cells, there are two types of Chromatophores. A Red-yellow one, and a Blue-white one. They affect what colour the chameleons skin is by growing or shrinking.

Whether it's through a chemical change, or a computer receiving data, we see colour due to the mechanics of our eyes. Nature deems hue differences to be very important, but outside of camouflage, what are the other practice uses?

We could explore the affects of different hue for the rest of our lives, or we could simply appreciate the beauty it gives the world.