Re: Subject: photogravures
Re: Subject: photogravures
- Subject: Re: Subject: photogravures
- From: Steve Upton <email@hidden>
- Date: Wed, 24 Oct 2001 02:06:18 -0700
At 9:08 AM -0400 10/23/01, Tom Lianza wrote:
Hi All
David Wollmann wrote:
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I must be seeing the effects of
metamerism because the prints look one way in my viewing
both, other way under tungsten, fluorescent and still
different in daylight.
I have not experienced this with my color prints only these
monotone gravures, does this sound like metamerism?
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There seems to a consistent misunderstanding about metamerism that seems to
run through the ink jet industry and then get reinforced by some
contributers to this group.
What David is seeing is precisely what Leonardo daVinci recognized in the
15th century: The color of an object is effected by the color of the objects
that illuminate it.
It is possible that the use of the term metamerism is not totally
correct in this case but I am certain that we are referring to a
phenomenon that is different than the simple "it looks different
under different lighting".
The "metamerism" to which we are referring is the problem where an
ink combination looks unpredictably different under various lighting.
So we are not talking about neutrals looking cooler under daylight vs
incandescent. We're talking about neutrals shifting to a strange
green or magenta under daylight (if balanced to incandescent as in
this example)
According to most definitions I have read so far, metamerism
typically refers to two separate patches that look the same under one
lighting condition but different under another. This is the result of
the patches having different spectral curves that produce the same
tristimulus values (colors) under one light but different under
another.
I personally think it is fair to call the neutral-shift metamerism as
well. When printing neutrals, the inks are balanced so as to appear
neutral under a certain lighting condition. Their combined spectral
curves produce Lab values near x,0,0 (we hope). When viewed under new
lighting, the balance is thrown off a surprising amount, resulting in
a color cast. My argument for calling this problem metamerism is that
we are still dealing with multiple pigments and their differences, we
just overlay them for a combined effect. The spectral vs. tristimulus
problem/issue is still there, still producing the differing effects
in our eyes.
Regards,
Steve Upton
________________________________________________________________________
o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX
o email@hidden 206.985.6837
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