What is metamerism?
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 us
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 OB
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.
