Re: Color Measurement
Re: Color Measurement
- Subject: Re: Color Measurement
- From: "Mike Eddington" <email@hidden>
- Date: Tue, 21 Jul 2009 14:43:22 -0400
- Thread-topic: Re: Color Measurement
>>it is important to note that it's not the Just Noticable Difference
JND that is in question here, but the non-uniformity of the color spaces
used that lead to other results. If CIECAM02 is a nearly visual uniform
space, one could say that one unit represents one JND. CIELab
definitively isn't, so a JND might be represented by other unit values
(bigger or lesser than one, depending on the color).>>
As far as I know, there isn't yet a functional color difference
methodology based on CIECAM02 publically available, is there?
Even if there were, other visual attributes (viewing conditions, gloss,
texture, etc) could add to "noticable differences" unaccounted for in
measurement.
>>I do not have a reference for the rule of thumb that dE2000 is about
half of dE1976. It was a verbal conversation at the Color Imaging
Conference a few years ago. Like all rules of thumb, large tolerances
are often involved.>>
I've seen the "JND of 0.5 for dE2000" mentioned before, notabliy in the
FAQ section of RIT's Munsell Color Science Lab. I'm just having a hard
time finding instances where I can legitimately perceive visual
differences between two samples with a dE2000 under 1 where I have many
instances where this is obvious with a delta E of 1. I also don't
completely understand the logic behind a global lowering of the JND when
the the smaller values is the result of a closer alignment to visual
perception.
I'm surprised there aren't many (any) tudies on this related to the
graphics arts. Interstingly, studies of color difference values vs
perception have been conducted in other industries. Like this one:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1989157
You can bet if I'm found in a dentist's chair undergoing resotorative
procedures, I'm going to verify the use of dE2000 when matching resin
composites (through the novacain and drool if necessary). ;)
Mike
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