Metamerism (color)

Metamerism (color)

In colorimetry, metamerism is the matching of apparent color of objects with different spectral power distributions. Colors that match this way are called metamers.

A spectral power distribution describes the proportion of total light emitted, transmitted, or reflected by a color sample at every visible wavelength; it precisely defines the light from any physical stimulus. However, the human eye contains only three color receptors (3 types of cone cells), which means that all colors are reduced to three sensory quantities, called the tristimulus values. Metamerism occurs because each type of cone responds to the cumulative energy from a broad range of wavelengths, so that different combinations of light across all wavelengths can produce an equivalent receptor response and the same tristimulus values or color sensation.