Strangeness of Colour and its Implications

Our eyes perceive light. Our brains interpret it into shapes and forms that we are familiar with. What we see is lighter or darker depending on how much of light enters the eye (that is; intensity) and is applied with "colours" based on the flavours of light we receive.

As vivid as they may be, these so called flavours of light are physically non-existent in nature. They are solely an interpretation that exists only within our perception.



And this has been at the base of the age old questions "Is my red the same as yours?" or "Do we perceive the same colours the same way?” Both to which the most sensible answer would be: "we'll never know".

What does a Colour Represent?

There is a unique colour for almost each and every frequency in the visible range of spectrum of light. Beyond this range, we see the colour "black". It is simplest to assume that colour depends on a physical property of light which is the frequency/wavelength of light.


While this is a fairly reasonable explanation, it fails to answer some of the more interesting aspects.

Colour Vs Wavelength

1. If all colours represent a corresponding wavelength, then what wavelengths do black and white correspond to?
2. When 2 or more colours are mixed, a new colour is formed. Does that means a new wavelength is produced by mixing different wavelengths?
3. Why can't be Red, Green or Blue colours be reproduced by mixing any other colours?
4. Resulting colours produced by multiple wavelengths depend on the intensity of one over the other. Why do the results of combinations depend on quantities? For example, when a red and a green light are used, a yellow colour can be observed. This colour can be made orange by increasing the amount of red light. Similarly, a greenish hue can be produced by increasing the amount of green light; both without altering any of the original wavelengths.

Additive Colour Mixing Example

Red, Green, Blue Model

Therefore, it is very unlikely that colour is a direct representation of frequencies or wavelengths of light. It is observed that Red, Green and Blue wavelengths are unique on their own while being able to recreate all the other colours by combining with each other. This suggests that our perception of colour is driven based on these 3 colours also known as the 'Primary Colours'.


Interestingly, our eyes have 2 types of light receptors on the retina (the screen where the image falls and then transduced to nerve impulses); "Rods" which are responsible for black and white vision and "Cones" for Colours vision. In fact, colour perception is indeed done by 3 different pigments each more sensitive to Red, Green and Blue. Overlapping of their sensitivities allows new colours to be formed.


Thankfully, this has allowed us to implement a full colour experience through digital screens and displays all by carefully mixing the 3 primary colours which otherwise would have been impossible to achieve.