Skip to main content

Colour theory: A jargon-free designer's guide

Colour theory
(Image credit: Steve Johnson on Unsplash)

Colour theory is a crucial part of designers' and artists' practice. However, colour is such a pervasive part of everything we visually encounter in the world that for many, it becomes an intuitive choice. 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). 

Understanding how colour is formed and, more importantly, the relationships between different colours, is one of the most vital art techniques to master. It can help you use colour more effectively in your designs, and make sure you pick the right palette for your projects. In this guide, we'll walk through what you should know about colour theory, including explaining any design terms you might not be clear on. 

While you're here, you also might want to check out our guide to how to manage colours in Photoshop.

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 all the important aspects of colour theory you need to help you start making informed decisions.

Colour systems

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.

01. Additive

Colour theory: RGB

Additive colour is based on red, green, and blue – RGB for short

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.

02. Subtractive

Colour theory: CMYK

Subtractive colour is based on cyan, magenta, and yellow (Image credit: Creative Commons)

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

(Image credit: Creative Commons)

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. These early wheels plotted the different primary colours around a circle, mixing different primary colours together in strict ratios to achieve secondary and tertiary colours.

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.

Each of these relationships can produce pleasing colour combinations. There are many more pleasing relationships between colours based on their position on the wheel. 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...