Altana BYK byko-spectra basic Instrucciones De Uso página 14

Detecting "Metamerism"
Detecting "Metamerism"
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When two color samples match under one light
source, but not under one or more other light
sources, the "color-match" is metameric. This
means that the colorant formulation in one sample
differs from the formulation in the other, resulting
in differing spectral reflectance factor curve
shapes. A metameric color match can also be
referred to as a "conditional" color match, since
the quality of the color match is conditional to the
type of light source under which it is viewed.
While it may not be possible, with the colorants
available, to completely eliminate metamerism,
the byko-spectra basic provides colorists with
the means of visually "indexing" the degrees of
metamerism under three spectrally dissimilar light
sources. The formulation may then be adjusted
to provide the "best match" under a specified
lighting condition, or the least metameric match
under all three lighting conditions.
For obtaining the best correlation with
instrumental measurements, calculated color
differences and metameric indices, the spectral
power distribution of the sources in the booth
should be used in the computations.