Nigel Wood Photography - cobwood studio

Colour Theory

Colour Spectrum

In discussing colour it’s usual to start with the traditional artists’ palette of primary colours – red, blue and yellow – and then progressively mix them to produce secondary colours, then tertiaries and the full artists’ colour wheel. However, in modern times we are perhaps equally familiar with the “additive” primary colours – red, green and blue – used in digital cameras and computer screens. Then again, in the printing industry, the primary inks are cyan, magenta and yellow. All a bit unhelpful…

However, as photographers we are not so concerned about how to create colours in paint or ink – we are more concerned about how colours in the real world interact emotionally when we capture them in a photograph. So is there a way to come to colour theory from a photographic perspective?

The natural spectrum of colours is found most dramatically in the rainbow:

rainbow
rainbow

As we all learnt at school, the colours are made by different wavelengths of light, from long wavelengths at the red end to shorter wavelengths at the blue / violet end. The visible spectrum is just a part of a broader spectrum, which extends to even longer wavelengths in the infra-red and shorter wavelengths in the ultra-violet.

What can we observe, looking at this spectrum? First, the colours all fade seamlessly from one colour to the next – from red to orange to yellow and so on, with no obvious boundaries. So we can think in terms of colours that are close together being in harmony – while colours that are further apart can contrast, notably the contrasting pairs of red & green and blue & yellow.

There is a separation between “warm” colours at the red end (the colour of fire) and “cool” colours at the blue end (sky, water, ice). Also, the colours seem to have differing brightness, with yellow and orange much brighter than blue and violet – and red and green in between.

Johann Wolfgang (von) Goethe (1749 – 1832), the German writer and scientist, conducted detailed studies of colours and published his Theory of Colours in 1810. He assigned brightness values to colours, indicating how much of one colour would balance another colour in a scene. His colour values were: yellow 9, orange 8, red and green 6, blue 4 and violet 3. So for example, when blue and orange occur together in a composition, the area of orange should be half that of blue (as orange is considered to be twice as bright). He also discussed the concept of colours having opposites: “Let a small piece of bright-coloured paper or silk stuff be held before a moderately lighted white surface; let the observer look steadfastly on the small coloured object, and let it be taken away after a time while his eyes remain unmoved; the spectrum of another colour will then be visible on the white plane.” (Theory of Colour) This is an easy experiment to try at home and reveals pairs of “opposite” colours, for example:

  • blue and orange
  • yellow and purple
  • red and green

To visualise this concept of colours having “opposites”, we need to join the artists by introducing a colour wheel. A remarkable aspect of nature helps here; the violet colours at one end of the spectrum work in visual harmony with the reds at the other end. If we wrap red onto the violet end of the rainbow, there is no discontinuity at all:

extended rainbow
extended rainbow

Now it becomes a simple matter to draw this rainbow spectrum as a circle, starting and ending at red – a colour wheel:

colour wheel 1
colour wheel 1

We can immediately see how blue falls opposite to orange, yellow opposite purple and red opposite green – as Goethe observed. Indeed for every hue in the spectrum, we can visualise an opposite. Taking this a step further, if we make a second, slightly smaller wheel and rotate it half a turn, we can show the strong contrasts between opposing colours all along the wheel:

colour wheel 2
colour wheel 2

Colour Relationships

The observation that colours that are opposite each other in the colour wheel seem to work in harmony gives rise to the expression that the colours are “complementary”. This is a harmonious contrast:

complementary colours
complementary colours

In the picture below the orange and yellow of the sailing boat work well with the blue sea background and the areas are roughly in line with the observations of Goethe, i.e. orange is perceived as twice as bright as blue and balances when it takes up half as much area.

complementary
complementary

Colours that are adjacent on the colour wheel also work well together and are referred to as “analogous”. These may be a range of cool hues around the blues, warm hues around orange, earth hues and so on. A scene with analogous hues will likely look relaxed:

analogous colours
analogous colours
analogous colours
analogous colours

On the other hand, if colours are spaced about a third of the way around the colour wheel (known as a “triad”), there will be high contrast and energy between the colours.

triad of colours

triad of colours
triad of colours

With an analogous colour scheme, it can be effective to have an isolated area of colour that is either complementary or high-contrast as a “colour accent”. In the picture below, the leader’s red t-shirt puts vibrance and energy into a picture that is otherwise a calm green – yellow landscape:

colour accent
colour accent

Postscript

I think we have seen that for photographers it is not necessary to think in terms of primary and secondary colours and so on. We are capturing the colours as we find them, not creating them from pigments. We can then move straight to the concept of a colour wheel based on the natural spectrum of the rainbow and thence to an understanding of colour theory and relationships.