Re: Color Measurement
Re: Color Measurement
- Subject: Re: Color Measurement
- From: Robin Myers <email@hidden>
- Date: Sun, 19 Jul 2009 18:33:23 -0700
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.
However, the dE1976 of 1 unit being a JND has never really worked. In
the near grays, it has often been my experience that 1/2 to 1/4 unit
is a JND depending on the difference direction vector and position in
the color space.
What all of this boils down to for me is that there is a large body of
work left to be done on color difference metrics.
Robin Myers
On Jul 18, 2009, at 12:21 AM, Graeme Gill wrote:
Robin Myers wrote:
Just as the scale changes in going from dE 1976 to dE 2000, the
tolerance range also changes. Where 1 dE 1976 was "roughly" assumed
to be a Just Noticeable Difference (JND), now that number should be
about 0.5 dE for a JND in dE 2000. As the scale changes, so does
the interpretation.
Do you have a reference for this ?
Looking thought the "The Development of the CIE 2000 Colour
Difference Formula: CIEDE2000"
and "The CIEDE2000 Color-Difference Formula: Implementation Notes,
Supplementary Test
Data, and Mathematical Observations" it isn't obvious that there is
any intention
that the JND threshold be different.
This plot also seems to contradict this idea:
<http://www.digitalcolour.org/Difference.htm>
ie. differences of about 1 CIE 1976 DE are also close to 1 CIE
DE2000 in
near the neutral axis.
Graeme Gill.
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