Re: Evaluation of Color Difference Formulas
Re: Evaluation of Color Difference Formulas
- Subject: Re: Evaluation of Color Difference Formulas
- From: Klaus Karcher <email@hidden>
- Date: Thu, 19 Jul 2007 21:48:55 +0200
dpascale wrote:
[...] there is a concensus in the scientific community that the
CIEDE2000 color difference formula is the best... ...on average.
... on average color differences? on average viewing conditions? or both?
Do you think color difference formulas with additional parameters that
account for different viewing conditions (like CAMs) could be useful in
this context?
Can you tell anything about
<http://www.imaging.org/store/epub.cfm?abstrid=22169> or
<http://www.iscc.org/ISCC2007/abstracts/T11IG1_Xue.pdf> ?
http://www3.interscience.wiley.com/cgi-bin/abstract/94518332/ABSTRACT
thanks :)
You have seen, I have seen, and many others have also noticed, that all
formulas "fail" at some point or another, either when looking at a
display or comparing print samples. However, it is dangerous to
globalize a formula quality by sporadic exposure to "bad" cases, as we
tend to forget the other, usually much more numerous, cases, where we
take the formula results and agree with them without questioning.
I am aware of this danger and I can't rate whether Timo Autiokari's
examples are a collection of sporadic bad cases or point out systematic
errors.
Anyway -- the first time I looked on a image with color pairs ordered by
DE00, I was very astonished how bad this sequence corresponded with my
perception -- see <http://digitalproof.info/FOGRA39/fo27vs39.tif> (1,9MB
Lab-TIFF). I assumed it was because of 8-bit quantization errors, gamut
issues, simultaneous contrast or any other of these countless color
appearance mysteries.
But now I see a new aspect: Maybe Phenomena like the Hunt Effect
(colorfulness increases with luminance), the Stevens Effect (contrast
increases with luminance) and the Helmholtz-Kohlrausch Effect
(brightness depends on cromaticity) affect the validity of Color
Difference Formulas in different viewing conditions more than I expected.
Are there any studies about it? (I guess there are).
Regards,
Klaus
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