Colorimetry is concerned with the measurement of, and discrimination between, colours. These are important topics in a wide range of the physical sciences, life sciences, and computing and engineering. Examples of specific areas where the techniques of colorimetry are used are: manufacturers of paints, textiles, plastics and cosmetics (and quality controllers in these industries), those interested in the effect of light in human environments (for example, in terms of its direct effects on the eye, laser safety and design of eye protection and ergonomics of hospital lighting), psychology, physiology and those involved in the technical aspects of photography. The book presents the physiological background behind how colour is perceived and discusses sources of visible radiation, before going on to describe in detail colorimetric techniques for measuring and discriminating between colours. Applications of these techniques are discussed and relevant mathematical data is provided. The book gives a comprehensive account of the physiological aspects of colour, the development of photometry and colorimetry, and applications of colorimetry in a single volume.