Re: Color difference equations [was: Color Measurement]
Re: Color difference equations [was: Color Measurement]
- Subject: Re: Color difference equations [was: Color Measurement]
- From: Mike Eddington <email@hidden>
- Date: Fri, 17 Jul 2009 08:15:23 -0400
- Thread-topic: Color difference equations [was: Color Measurement]
On 7/16/09 6:26 PM, "Marc Levine" <email@hidden> wrote:
Hi Mark,
> Hi all,
> Personally, I think that questions regarding dE formulas come up
> because it is unclear how to categorize variance. On one side, you
> have the variation built into the hard technology used to quantify and
> reproduce color: measurement devices, inks, papers. My opinion is that
> these things should be "scored" by non-eliptical formula: dE76. My
> reasoning is that the variation of a device should not be scaled
> against me. Variation of the device should be measured as an
> independent property. Some may say "but you'll never see that in the
> yellow". To me, that doesn't matter. Variation is a measure of
> accuracy and repeatability. It should have nothing to do with me.
Than perhaps it would be more accurate to determine a means to quantify
instrument/object variation using spectral response, eliminating the
transformation to a ³perceptual² color space utilizing standard observer and
illuminant models...if you want to eliminate the ³me² portion. After all,
CIELab is all about approximating human vision, however imperfect it is,
right? I¹m betting that spectral reflectance could be used to determine
instrument variation more accurately than equations based on CIElab, but
perhaps not by a means that is easily quantified by a ³JND² value. But if
the reported JND doesn¹t relate to visual perception, who cares ...besides
you and Terry I mean ;)? So for example, you could determine that two
instruments have agreement issues with dE76, but you may never see the the
difference.
Mike
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