Re: Another quote from Roy Berns on metamerism-color inconstancy
Re: Another quote from Roy Berns on metamerism-color inconstancy
- Subject: Re: Another quote from Roy Berns on metamerism-color inconstancy
- From: Ernst Dinkla <email@hidden>
- Date: Fri, 18 Jun 2010 09:48:36 +0200
Terence Wyse schreef:
On Jun 17, 2010, at 5:56 PM, Marco Ugolini wrote:
The quote DOES mention "a SINGLE SAMPLE viewed under multiple
illuminants". So, it's ONE The fact that we are dealing with one
single sample/specimen IS the whole point of the color inconstancy
concept.
Just to play devil's advocate then, what is the definition of "single
sample"?
For example, what if I took a neutral R=G=B image, separated it
multiple times using different levels of GCR such that under "D50"
they would all appear to be perfectly neutral. I then take take them
and either print them on a single press sheet or on a single inkjet
proof/print. I take this single sheet/print and look at it under
different illuminates(?) and lo-and-behold these different
separations printed using the same inks on the same substrate take on
different color casts due to the level of GCR in each image.
Would this be color inconstancy or metameric failure?
Terry
A 100% metameric match if you get the patches equal under one light
source. If you bring it then to another light source and they are no
longer equal you can call it a metameric failure. The conditions are
there. Two or more samples compared under different light sources. That
the samples are on one page, printed and using the same inks for all
doesn't matter.
If your example doesn't make a metameric match under any light source in
the universe you could call it "bad color mixing" instead. Which
suggests that the metameric failure could do with an extra rule: the
condition that the samples showing the metameric failure should be able
to make a metameric match under one light source at least. And I do not
mean a pitch black environment. It is very scientific and abstract to
put an apple green sample and an stone red sample underneath a
fluorescent lamp and declare that a metameric failure but who cares for
that observation? It also falls in the categories "color inconstancy"
and "bad color mixing" if the goal is to get them equal.
--
Met vriendelijke groeten, Ernst
Dinkla Gallery Canvas Wrap Actions
| Dinkla Grafische Techniek |
| www.pigment-print.com |
| ( unvollendet ) |
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