The word colorimetry is derived from Latin: color = colour and Greek: metron = measure. It is the science of measuring colour. There are broadly two types of colorimetry, the measurement of surface colours, such as painted metal, that are illuminated by incident light; and the measurement of light emitting objects, such as lamps.
Colorimeters typically consist of three light detectors, each with a spectral response corresponding to the tristimulus receptors (cones) of the human eye. The combined output of these detectors gives chromaticity values.
In order to separate different colours and avoid colour confusion, organisations recommend colour boundaries shown on a CIE 1931 chromaticity diagram (see figure to the right).
Visible Spectrum Plots
