What is metamerism?

Metamerism is a psychophysical phenomenon commonly defined incorrectly as "two samples which match when illuminated by a particular light source and then do not match when illuminated by a different light source." In actuality there are several types of Metamerism, of which the first two described below are most commonly referred to and also most commonly confused: Sample metamerism: When two color samples appear to match under a particular light source, and then do not match under a different light source this is "sample metamerism." One can conclude that the spectral reflectance distributions of the 2 samples differ slightly, and their plotted reflectance curves cross in at least 2 regions. By illuminating them with lights with consideralby differing spectral power distributions you can witness and even exaggerate the visual differences between the 2 samples. The example below is how most remember this is the most commonly experienced form of metamerism. Example: most people have ...  more

Metamerism is an effect created when objects having different spectral distributions look alike under one light source but appear different when viewed with a dissimilar light source. Metamerism is most frequently seen when two colored objects match in daylight, but differ markedly in color when viewed in tungsten-filament light. This arises because the visible absorption spectra of the two objects differ significantly, although the tristimulus values in daylight are identical (the colors have the same set of color coordinates but different spectral reflec tance curves). Pronouncing "Metamerism": me*tam*er*ism (just in case you wanted to talk intelligently with others on this subject -- hey, we never knew how to pronounce it until just last week ;-) Click to HEAR this word spoken... AIFF format WAV format Examples of Metamerism in 2000P Output: John Custodio of New York City sent us some great examples of metamerism. John supplied us with a grid of his images and color patches that ...  more

This refers to a situation where two colors will appear to look alike or match each other under one set of conditions but do not under another. Metamerism is generally experienced when viewing two samples under different light sources. Colors are more apt to match when viewed in daylight or under daylight balanced lights. On the other hand, these same colors are more prone to be different under tungsten-filament or possibly other forms of illumination.  more

Harald Johnson defines metamerism as a normal phenomenon relating to how the human eye perceives color. It occurs when "two different color objects have the same color appearance to a normal human viewer under one light source (metameric match) but look different under another light source (metameric mismatch)." (*1) To a printmaker, this means that the painstakingly precise color information applied to each print will be compromised whenever that print is viewed under a different light source. Thus, one primary goal of any printmaker should be to avoid metamerism in order to validate the time spent on color management and to uphold the integrity of the reproduction. After all, what good is a reproduction if it does not closely match the original? Now that we understand metamerism and why it should be avoided, how do OBAs fit into the picture? When OBAs are exposed to UV light, the treated paper appears brighter and whiter. When OBAs are not exposed to UV light (in the evening), the ...  more

Metamerism refers to the situation where two color samples appear to match under one condition but not under another; the match is said to be conditional. Metamersim is usually discussed in terms of two illuminants (illuminant metamerism) whereby two samples may match under one illuminant but not under another. Other types of metamerism include geometrical metamerism and observer metamerism. Two samples that conditionally match are said to be a metameric pair. If two samples have identical reflectance spectra then they cannot be metameric - they are an unconditional match.  more

Everyone is familiar with this effect: a colored object appears to be one color under a given illuminant, (e.g. daylight), but appears differently under another illuminant such as the light from an incandescent light bulb. This change in color, which occurs frequently with almost all colored objects, has been erroneously called metamerism. But what is the true definition of metamerism? We use the term metamerism when the colors of two objects under the same illuminant, e.g. daylight, (D65) are perceived to have the same color under one illuminant, such as daylight, but have different colors under a different illuminant, such as an incandescent light bulb. This is usually an unwanted effect. Just imagine you have a blue jacket and the materials used for the sleeves and back exhibit metamerism the jacket would look perfect in daylight, but in the evening in the light from an electric bulb the sleeves would appear to be a completely different color. This effect can be explained clearly ...  more

When two colors look the same under one light source but look different under another light source. Metameric colors are sometimes called “conditional color matches”.  more

A thread about this aspect of color theory is here: /forum/remark,13894757  more