COLOR  PHENOMENA Page: 11. 01
Introduction Ingredients Spectra Attributes The Human Eye Color Mixing General Terms
Color Spaces How to measure Color Scales Color Effects After Images Contents

Color Effects

COLOR CONSTANCY on page 11.00

COLOR METAMERISM on this page
SUCCESSIVE CONTRAST on page 11.02
SIMULTANEOUS CONTRAST and VISUAL ILLUSION on page 11.03
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COLOR  METAMERISM

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A layman can recognize metamerism when two colored objects that match 
under one illuminant fail to match under an other illuminant.

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Metamerism is present when two colored objects having the same 
color appearance nevertheless have different spectral curves.

 


11-01-01

Sample B has more red, more green and more blue reflection
and less yellow and less violet,
compared with Sample A.  

 


11-01-02

Sample A and Sample B give a precise color match under 
"Illuminant D65" conditions.

 


11-01-03

Sample A and Sample B do not match under 
"Illuminant A
" conditions.

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If two colored samples have identical spectral curves or reflectance spectra then they 
cannot be metamerism. They are an unconditional color match.

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It is impossible to match an exact copy of a color with another 
composition of components than of which it contains originally.
 

For instance: 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.
 

T
he 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. 
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EXPLANATION

"daylight"  (C)

An approximation of overcast daylight having a color temperature of approximately 6750 Kelvin and obtained by a combination of Light Source (A) and a special filter. 
The old standard illuminant for color measurement.  

"bulb light"  (A)

A tungsten filament lamp operated at a color temperature of 2854 Kelvin, approximately a blackbody operating at that temperature.  
A
standard illuminant for color measurement (less blue more red)

"Illuminant D65"

The D class of illuminants specify relative energy distributions that closely correspond to the radiation emitted by a so-called black-body. As the tempertature of a black body is increased there is a shift in the emitted radiation to shorter wavelengths. A specific D illuminant is therefore notated with reference to the temperature (in Kelvin) of the black-body which it most closely matches. For example, the illuminant D65 has a spectral energy distribution that closely matches that of a black-body at 6500K. Illuminant D65 also closely resembles the relative spectral energy distribution of north-sky daylight and is accordingly important for color specification in northern Europe. Other D illuminants, notably D55, are important in other parts of the world.

 "Illuminant A "

Illuminant A is realized in the laboratory by Source A, the radiation from a gas-filled tungsten-filament lamp of the same correlated color temperature.
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 Last update
2010-05-18