Introduction: what is colour?
Colour is how we describe the visible features of an object by its hue, lightness, and saturation. In physics, we identify colour by measuring a range of wavelengths known as the visible spectrum (See Figure 0.1). We also call this light or electromagnetic radiation. The human eye perceives these visible wavelengths as different colours.
The visible light spectrum measured in nanometres (nm).
In this open educational resource, you can find information on colour theory divided into three chapters. This resource also includes quizzes to test your knowledge, and practical learning activities to guide users in applications of colour theory for art and design. The content is relevant for anyone working with colour in creative and scientific fields.
Each chapter covers information on the following topics:
An introduction to colour theory history with a summary of selected key scientific developments. Also covered are short introductions to cultural interpretations of colour and colour aesthetics.
- Scientific discoveries relating to colour
- Cultural interpretations of colour and colour symbolism
- Colour aesthetics in art and design
A scientific approach to the visible spectrum and how humans and other species perceive colour.
- Introduction to current scientific theory of the visible spectrum, physics, optics and chemistry
- Anatomy of the human eye: how we see and interpret colour information in the brain
- Colour blindness and other vision differences
- Colour vision in animals
Detailed explanations of different colour systems for the practical applications of colour in physical materials and digital media.
- Understanding additive and subtractive colour
- Understanding colour systems for working with:
- digital media,
- printing, and
- colour pigments and dyes
- Using colour wheels and creating colour relationships
A list of all the glossary terms used throughout this resource. You can view all glossary term definitions on a single page at the end of the resource, or select individual terms throughout the text as you are reading.
Hue is the term that we use to classify colour. For example if we describe something as "red" or "magenta" or "greenish-yellow", that is the hue. In physics, a specific wavelength of light is a hue. Black, white and grey are not hues, although we may call them colours in a practical sense, for example, when referring to coloured paints or fabrics.
Lightness describes lighter and darker variants of a colour. The lightest "colour" would be white, and the darkest would be black.
Saturation is the intensity of the colour. Saturated colours appear very vibrant, whereas de-saturated colours tend towards white or grey. A black and white image would have zero colour saturation. Saturation does not relate to how light or dark a colour is.
Electromagnetic radiation is made from waves of the electromagnetic field. It includes radio waves, microwaves, infrared, light (including the visible spectrum), ultraviolet, X-rays, and gamma rays.
