Metamerism (color)

In colorimetry, metamerism is a perceived matching of colors with different (nonmatching) spectral power distributions.

[2] Normally, material attributes such as translucency, gloss or surface texture are not considered in color matching.

This alters the relative importance of different wavelengths in a spectral power distribution to each observer's color perception.

Field-size metameric failure or field-size metamerism occurs because the relative proportions of the three cone types in the retina vary from the center of the visual field to the periphery, so that colors that match when viewed as very small, centrally fixated areas may appear different when presented as large color areas.

Colorimeters basically consist of a combination of a matrix of sensor cells and optical filters, which present an unavoidable variance in their measurements.

Two stimuli with a high degree of metamerism are likely to be very sensitive to any changes in the illuminant, material composition, observer, field of view, and so on.

[4] Another metric, for daylight simulators, is the MI, the CIE metamerism index,[5] which is derived by calculating the mean color difference of eight metamers (five in the visible spectrum and three in the ultraviolet range) in CIELAB or CIELUV.

[citation needed] Due to the wide range of different illuminants in modern life, textile color matching is difficult to ensure.

Metamerism on large textile items can be resolved by using different light sources when comparing colors.

This difficulty arises due to the necessity of a microscope, which has one single illumination source, to observe these small fibers.

Then, one selects a set of ink compositions corresponding to the color reflectance factor, which are used by the inkjet printer for the reproduction.

Sometimes, however, one reaches the conclusion that an improved match is not possible with the materials available either due to gamut limitations or colorimetric properties.