Talk:Metamerism (color)
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[edit] Mathematical definition
Can someone define the loci of metamers on a chromaticity diagram or otherwise define metamers mathematically?--Adoniscik (talk) 02:27, 16 December 2007 (UTC)
[edit] Color Metamerism
A layman can recognize color metamerism when two colored objects that match under one illuminant fail to match under an other illuminant.
Color metamerism is present when two colored objects having the same color appearance nevertheless have different spectral curves.--No, 2 lights with different spectral poser distributions are actually metameric, in which case the sample is not in question as being metameric or not.
If two colored samples have identical spectral curves or reflectance spectra then they cannot be metamerism. They are an unconditional color match.
True. but don't forget the light
It is impossible to match an exact copy of a color with another composition of components than of which it contains originally.
An example: The color of a ceramic object contains the coloring components A & B. It goes without saying that a plastic accessory has to be manufactured in the same color as the ceramic object. The coloring components A & B are pigments which both are resistant to high temperature often more than 1200 degrees Celsius. For the plastic accessory other pigments as A & B have to be used in order to give a good like color as the ceramic object. The task of the colorist is to chose pigments to compose a color mix in such a way that the plastic accessory has a resemble color in relation to the ceramic object. An experienced colorist is capable to colored the plastic accessory so that the consumer is satisfied and will accept the color copy when it match to the ceramic object under normal conditions of light-circumstances.
[edit] Veracity
Apart from the initial definition, the majority of the existing metamerism page seemed to be filled with the common confusion between "metamerism" and "metameric failure". The incorrect usage of the term metamerism is widespread, perhaps due to its use as a sloppy way of indicating that the mechanism of metamerism is involved in a metameric failure, or perhaps due to the confusion caused by the fact that metameric matches that are strongly metameric, are most prone to metameric failure. A great deal of (IMHO) relatively unrelated content is also present, most of which has a stronger relevance to other color phenomena (ie. gamut mapping, reflective colors dependence on illuminant color, Color appearance etc.)
The reference to the www.thepapermillstore.com page is yet another reference to incorrect usage, as is opening paragraph on this page.
As a result I've attempted to correct most of the usage, remove superfluous discussion, and supply some more relevant points, such as mentioning spectral color matching, so that this entry can guide people in the right direction. I hope the entry now more strongly represents the definitions and understandings gained from authoritative works, such as Wyszecki & Stiles. GWG
[edit] Fishy / incorrect sentence?
Article says:
"For any given light stimulus, regardless of the form of its spectral emittance curve, there always exists a unique mixture of three "primary" lights that when added together, or added to the stimulus, will exactly match it, provided the lights are adjusted to have equal brightness."
This doesn't seem right on a number of grounds. Given a certain red, green and blue, you cannot match all tristimulus values. And if you try anyway, you won't get anywhere by adjusting the lights "to have equal brightness"...the whole point is that their brightnesses are individually adjusted. Can someone correct this if indeed it's wrong, or explain it better if it's right? Thanks! --Steve (talk) 20:45, 16 July 2008 (UTC)
- Yes, the equal brightness bit is bogus. The point is that depending on whether the stimulus to be matched is inside or outside the color triangle, you might need to add some primary to the stimulus to match some other mixture of primaries. Try to say that... Dicklyon (talk) 21:40, 16 July 2008 (UTC)
[edit] Too much and too little
This article fails to identify common instances of Metamerism found in gemstones, yet consists of a complicated explanation that seem to be cribbed from a textbook. Fred Talk 14:48, 6 September 2008 (UTC)
