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Re: Metamerism vs Color Constancy
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Re: Metamerism vs Color Constancy


  • Subject: Re: Metamerism vs Color Constancy
  • From: <email@hidden>
  • Date: Tue, 20 Sep 2005 15:36:57 -0400

Marco,

You say:
If I can try to draw a conclusion from what you say, then, when we refer to
the change in appearance of a print under different illuminants it would be
more appropriate to say that that specific print is "color inconstant."

That would be appropriate.

It is good to see that overall, the responses you got from all "converge" to the same understanding of the concepts.

It was also fun to see a reply mentioning the "old" photographers' problem of greens becoming brown, very similar to the example I mentioned.

Have a good day,

Danny Pascale

dpascale AT babelcolor DOT com
www.BabelColor.com

On Tue, 20 Sep 2005 12:14:27 -0700
 Marco Ugolini <email@hidden> wrote:
In a message dated Tue, 20 Sep 2005 09:25:25, Danny Pascale wrote:

A more likely case for both metameric match and color
inconstancy would be for two shades of a color (I have
measured this for kaki green paints of the same
manufacturer for instance). You can look at this screen
shot that illustrates this example:
http://www.babelcolor.com/main_level/screen_shots/Spectral_Tools_MI.htm

Since the two shades are made of the same pigments, there
is basically no metameric effect between the two (i.e. the
color relation or color difference remains the same for
various illuminants). However, these colors can be color
inconstant and become "browner" when seen under D50
relative to tungsten (Ambient 2775 K). Since they both
become "browner" at the same time, the relative hue,
saturation and brightness difference is about the same.


I hope this makes it clearer!

Yes, Danny, I think it does, and I thank you for taking the time to explain
this to me.


If I can try to draw a conclusion from what you say, then, when we refer to
the change in appearance of a print under different illuminants it would be
more appropriate to say that that specific print is "color inconstant."


Compared to you and other "color monsters" on this forum, my color science
is certainly more than a bit weeny: all the more reason for me not to
compound my relative ignorance by misusing the terminology. That's why I
sincerely thank you for clearing this one up for me.


--------------
Marco Ugolini
Mill Valley, CA

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 >Re: Metamerism vs Color Constancy (From: Marco Ugolini <email@hidden>)

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