Hello again!

In my first post (which you can find here) we left off with genius man Sir Isaac Newton conducting a great experiment which made rainbows appear on his walls.

By doing this, he proved many great things! However, this experiment also led him to creating a colour wheel or a circular diagram showing how colours relate to one another – kind of like this one over here to the right.

If we start at red on the left, we see the colour progresses to dark orange, light orange, yellow orange, yellow and so on from colour to colour – pretty self-explanatory right?

Well this is where we get to today’s topic – primary colours + their accompanying colour models. And we’re going to get started with some basics.

Primary colours are most simply described as colours that need not be mixed with any other colour to be created. They are the purest forms of that hue.

However (generally-speaking) you can mix primary colours to create any other colour you can dream of, which is a pretty great thing.

In Newton’s prism experiment, he decided that the three primary colours were:



R ed

Y ellow

Blue

This traditional trio of primary colours makes up the RYB colour model also known as the colour wheel model.

In between these primary colours on the wheel you’ll also find secondary colours. These are hues which are made from the two closest primary colours to them in the wheel.

For example:

Red + Yellow = Orange

Yellow + Blue = Green

Blue + Red = Purple (violet)

The remaining 6 colours left on the wheel are tertiary colours and are made by mixing primary and secondary colours together, it’s as simple as that!

Since Newton’s discoveries, science has progressed in leaps and bounds, and as we learn more about light, it’s motion and how it interacts with surfaces like the human eye, the RYB model has become almost redundant. It is now really only used in the fine art world when mixing tangible pigmented paints.

During these aforementioned leaps and bounds made by science, it was found that red, yellow and blue were not in fact the best colours to combine when it came to presenting media through electronic systems using light e.g. TV, computer screens or photography.

In fact, red, blue and green are known as light primaries and combine in different intensities to around 216 different colours suitable for use through electronic screens. This combination creates the RGB colour model.

The RGB model is also known as the additive model. This name refers to the addition of different intensities of red, green and blue superimposed (overlaid on each other). The colour seen is dependant on the intensity of each colour. Complete intensity will result in white (as seen in the middle of the diagram) whereas no intensity will result in black.

This colour model has been important since long before the explosion of technology. In the 1800’s, two scientists Thomas Young and Hermann von Helmholtz came up with the Trichromatic theory – that the way in which humans see colours is based on ‘colour receptors’ in our eyes – more specifically red, blue and green receptors.

It was only these three receptors that were needed to see any and all colours on the spectrum. They thought that when each receptor was active, you would see the respective colour. If two were active at the same time – say your green and red receptors were active, you would be seeing a yellow hue. To see white, all three receptors would be stimulated equally.

The Young – Helmholtz theory is still valid today explaining the aspect of colour vision associated with receptors.

Quite literally the opposite, the subtractive model is also known as the CMYK model – the third and final colour model we’ll be looking at today. It involves cyan (a funny word for bright, light blue), magenta (a funny word for bright pink), yellow and black, called pigment primaries and it is mostly used in the printing world with inks and dyes.

As we saw at the end of my first blog, white light is made up of all the colours in the spectrum. In the CMYK model, white light is reflected off of a surface that has varying amounts of cyan, magenta and yellow inks upon it (the amounts are dependant on the colour aiming to be produced). The inks interfere with the white light, more or less ‘break it up’ and therefore the light that gets reflected back, is seen as a colour.

On a piece of paper fresh out of the printer, the three colours are arranged in little dot patterns called rosettes that the human eye can’t make out unless looked at extremely closely. The CMYK colour model can actually produce many, many more colours than the RBG model because of this patterning.

So next time you go to fill up those (ridiculously expensive) printer inks yet again, or are about to paint the next Mona Lisa, or maybe just as you’re reading this blog and looking at all the pretty colours, think about these models, the clever people that created them, and how cool the world really is in colour.