Re: JND [was: Color Measurement]
Re: JND [was: Color Measurement]
- Subject: Re: JND [was: Color Measurement]
- From: Robin Myers <email@hidden>
- Date: Thu, 16 Jul 2009 10:14:25 -0700
However, in the example given by Klaus Karcher, the L*a*b* values
differed by 5 units in the b* values, the other values were the same,
and only dE 1976 correctly represented the dE as 5 units. For this and
other reasons, dE 2000 and dE 1994 are not recommended for dEs greater
than 5 units (it is not clear if this 5 unit threshold is in the dE
1976 space or the others). dE 1976 is still recommended for expressing
large dE values.
The unevenness of dE values throughout the color space is not due to
the dE 1976 equation but rather to the unevenness of L*a*b* space
itself.
Robin Myers
On Jul 16, 2009, at 8:45 AM, Marco Ugolini wrote:
Klaus Karcher wrote:
2) yellow -- distance rated more than 5 times
larger by DE76 than by DE00:
Klaus,
That's an excellent example of how a simply-built equation like
DeltaE 76 measures all differences across the CIELAB space as if
they were of equal importance -- and thus resoundingly fails to
account for the way human vision actually functions.
Marco Ugolini
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