Re: Metamerism vs Color Inconstancy, again
Re: Metamerism vs Color Inconstancy, again
- Subject: Re: Metamerism vs Color Inconstancy, again
- From: Klaus Karcher <email@hidden>
- Date: Thu, 24 Jun 2010 22:01:58 +0200
Ernst Dinkla wrote:
john castronovo schreef:
That's a vocabulary lesson that the lay person doesn't need to know,
but in here I think it's important that we agree on such terms because
it makes these posts easier and more clear in the future. Perhaps,
because I'm not a color scientist, I don't have enough information in
my head already to be confused by it. :o)
When Ben Goren asked for a good demonstration of metamerism his message
was perfectly worded for that request yet the first reply was one that
put dots on i's that were already dotted in my opinion. I think in the
next two messages they came to the same conclusion. However since then
the tap on orthodox citations of color bibles has been wide open.
Provoked by some messages without doubt, confused by some related
questions but also without no other objective than taking the higher
ground in what becomes a debating contest rather than an exchange of ideas.
Then when someone else opens a fire plug to take the debate to another
level of abstract thinking and terminology, we get the message that
there's already too much water spilled. In my opinion that first reply
wasn't even necessary and I still have some (to me) interesting questions
unanswered. Graeme is my champion but I wonder whether he actually wants
to dot the i's here or just finish this thread with the right method.
I don't mind if it goes either way.
Roughly by the time this discussion got dogmatic traits (thanks to
Marco's pontification), I had a very amusing talk with Alexander
Logvinenko (Research Professor at the Glasgow Caledonian University)
about Metamerism, Color Constancy and Color Inconstancy. We were sitting
in the Helsinki Airport Café on our way back from CGIV and he talked
about the same topic Graeme summarized so aptly:
"Color Constancy" seems to be used in the color and vision
literature for two distinct phenomena: one is the robustness
of a color under different illuminants - something that is strongly related
to metamerism, and the other is the human visual systems ability to
estimate and "see" the underlying color of things, discounting the
illumination conditions. [...]
There may be a slight bias towards using "Color inconstancy" for the
former, and "Color constancy" for the latter, but having one not be
the inverse of the other seems very confusing.
He recommended an article by Alan R. Robertson:
<http://www3.interscience.wiley.com/journal/114180297/abstract> and told
me about the (rare) occasions when scientists of different disciplines
meet at the same conference, using the same words (color constancy /
color inconstancy) with completely different meanings. Some talk
primarily about color /inconstancy/ in a sense merely related to
physical properties of light and sample plus chromatic adaptation) --
and others talk about color /constancy/ (in spite of "physical"
inconstancy) from a neuroscientific point of view. It might seem bizarre
when a physicist uses an example to demonstrate color /inconstancy/
while a neuroscientist uses nearly the same example to explain color
/constancy/. Alexander's statement culminated in the invocation:
"Please, scientists: talk with each other and try to settle on a
coherent terminology -- for the sake of your student's mental health!"
I'm very happy that Graeme broadened our view, pointed to the
contradictory meanings of "color constancy" and referenced the works of
McCann. Let us keep in mind that color is first and foremost a
perception and not a physical property. Even if it's often much simpler
to treat human vision like a camera sensor with some white balancing
capabilities, we should always be aware that this is a rough
simplification that does not represent the truth. /One/ meaning of
"color constancy" fits well into this simplified assumption, but the
other does not at all.
Klaus
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