Re: Epson 2200 inks
Re: Epson 2200 inks
- Subject: Re: Epson 2200 inks
- From: Roger Breton <email@hidden>
- Date: Thu, 15 Jan 2004 22:51:21 -0500
I wrote:
>
But, I don't think that Illuminant Metamerism is the determining factor here
>
and neither could the Metamerism Index be used to predict the change in
>
color appearance.
<snip>
>
I once read a page about "Color Constancy
>
Index" in Hunt's Measuring Color book (towards the end) but, for the life of
>
me, I could never figure out his presentation -- too theoric for me (then).
>
I did try to search the CIE site and the web many times for references on
>
Color Constancy index but it still eludes me.
The concept I meant to use above was "Color Inconstancy Index" and not
"Color Constancy Index" which has to do with chromatic adaptation. I am not
going to say more for now. Metamerism in the context of Epson's ink is no
doubt the wrong concept to use, neither 'Illuminant' nor 'observer'
metamerism are suited. I was (and still am) under the impression that "Color
Inconstancy" is the right concept but I am not sure anymore. The way I
understand the concept, two colors tristimulus values are brought under the
same illuminant for the sake of making a direct comparison. For example,
sample M measured under Illuminant A and sample P measured under Illuminant
D65. How can the two sample colors be compared directly? By converting
sample A tristimulus values to D65 illuminant through chromatic adaptation.
Then any color difference equation can be used to calculate the 'Color
Inconstancy Index' between the two samples.
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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