Colour theory is a crucial part of any designer's or artist's practice. For many, colour is such a pervasive part of everything we visually encounter in the world that it becomes an intuitive choice. Understanding how colour is formed and, more importantly, the relationships between different colours, can help you use colour more effectively in your designs, and make sure you pick the right palette for your projects.
If you think back to school, you'll probably recall being taught the basics of colour theory: there are three primary colours – red, yellow, and blue – and any colour can be created by mixing these three colours in varying quantities. It turns out that this isn't quite the whole story (although it's still workable enough to be taught to five-year-olds). In this guide, we'll walk through what you should know about colour theory, and explaining the jargon and design terms that come up along the way.
While you're here, you also might want to check out our guide to how to manage colours in Photoshop, or our guides to colour grading and art techniques. If you need software to put all this theory into practice, then we recommended you get Adobe Creative Cloud.
Colour theory: A designer's guide
The Bauhaus school understood the power of colour in the 1920s and 1930s, with staff and students going on to develop colour theories for evoking particular moods and emotions through choice of palette in design and architecture. (Take a look at our guide to Bauhaus design for more on this.)
The theory of colour is a discipline that stretches back much further than that – at least to the 15th century – and uses physics, chemistry and mathematics to fully define and explain the concepts. However, much of this is unnecessary to being able to use colour effectively. Here, we're going to offer more of a handy overview of the most important aspects of colour theory you need to help you start making informed decisions in your own work.
A colour system is a method by which colour is reproduced. There are two primary colour systems: additive and subtractive (also known as reflective). We use both on a daily basis. Screens use additive colour to generate all the colours you see, while books and other print materials use subtractive colour for their front covers.
In simple terms, anything that emits light (such as the sun, a screen, a projector, and so on) uses additive colour, while everything else (which instead reflects light) uses subtractive colour.
Additive colour works with anything that emits or radiates light. The mixture of different wavelengths of light creates different colours, and the more light you add, the brighter and lighter the colour becomes.
When using additive colour, we tend to consider the building block (primary) colours to be red, green and blue (RGB), and this is the basis for all colour you use on screen. In additive colour, white is the combination of colour, while black is the absence of colour.
Subtractive colour works on the basis of reflected light. Rather than pushing more light out, the way a particular pigment reflects different wavelengths of light determines its apparent colour to the human eye.
Subtractive colour, like additive, has three primary colours – cyan, magenta, and yellow (CMY). In subtractive colour, white is the absence of colour, while black is the combination of colour, but it’s an imperfect system.
The pigments we have available to use don't fully absorb light (preventing reflected colour wavelengths), so we have to add a fourth compensating pigment to account for this limitation. We call this 'key', hence CMYK, but essentially it's black. Without this additional pigment, the closest to black we'd be able to render in print would be a muddy brown.
The colour wheel
In order to make it easier to see the relationship between different colours, the concept of the modern colour wheel was developed around the 18th century. Although colours exist on a continuous spectrum, it helped artists to break them down into individual blocks that could be named.
Colour wheels show the primary colours (conventionally red, yellow and blue in painting) on the outermost ring. The secondary colours are created by mixing two primary colours – if red, blue and yellow are the primary colours, the secondary colours are green, orange and violet. Tertiary colours are then created by mixing a primary with a secondary colour.
Note that using red, yellow and blue as the primary colours is not entirely accurate since greens and blues actually take up more of the colour spectrum. As a result, sometimes alternative colour wheels are used, such as red, blue and green, or cyan, magenta and yellow. It is possible to mix traditional primary colours with these alternative colour wheels, though they won't be as intense as pure pigments.
The colour wheel allows us to see at a glance which colours are complementary (opposite on the wheel), analogous (adjacent on the wheel), triadic (three colours positioned at 120 degrees on the wheel from each other) and so on (see below). Each of these relationships can produce pleasing colour combinations, and there are many more pleasing relationships between colours based on their position on the wheel.
Complementary colours sit opposite each other on the colour wheel. These pairs have the highest colour contrast, so they often look very intense when placed next to each other. Two saturated complementary colours can sometimes clash and strain a viewer’s eyes, especially in close proximity, so it can be better to ensure that one of them is more neutral if you're going to use them together.
Mixing two complementary colours together produces a neutral grey, or even a black, as they cancel each other out. The greys in the centre of the colour wheel can be created in this way.
Analogous colours sit next to each other on the colour wheel, so they have less colour contrast and therefore harmonise easily. In fact, sometimes they harmonise too easily, which means you might want to add contrast in these sorts of combinations, for example by pushing the tonal or saturation contrasts (or both).
When mixed together, analogous colours produce bright intermediary hues. The closer two colours are on the colour wheel, the more intense their mixture is. The further apart they are, the duller the mixture.
Triadic schemes comprise three colours that are evenly spaced around the colour wheel. This type of scheme can be challenging if you're using saturated colours as it will include a large area of the wheel, which makes colour contrast hard to manage. One solution is to pick a dominant colour and let the other two support it as more subdued tones.
Another option is to tie a triad of saturated colours together with whites. This allows the eye a break and reflects subtle indications of the triad. Alternatively, triad colours can be used in small amounts to ‘spice up’ neutral arrangements.
Split complementary colours
Split complementary colour schemes are like complementary schemes, but in this case, one of the colours is split into two. The other colour sits opposite the centre point of this pair. The separation between the split pair can be narrow or can expand until it transforms into a triadic scheme.
This kind of scheme is a good option for a limited palette because it offers the harmony of a complementary colour scheme while covering more ground on the colour wheel and including a wider range of colours. Complementary schemes sometimes split both colours (this is sometimes called a tetradic scheme). They work especially well if the range of each pair is limited.
There are free apps for picking a colour scheme, or you could use your designer's eye to pick your own. Click through to the next page for a little help on this.
Next page: the three components of colour, colour gamut, and more...