Re: JND [was: Color Measurement]
Re: JND [was: Color Measurement]
- Subject: Re: JND [was: Color Measurement]
- From: Terence Wyse <email@hidden>
- Date: Thu, 16 Jul 2009 13:37:20 -0400
But Robin, doesn't that exactly illustrate the point that 5 dE on a
saturated yellow is completely different (almost imperceptible) than 5
dE on a neutral gray?
dE(76) seems to imply that they are the same visual color difference
when they most certainly are not. Whether this "difference" is caused
by deficiencies in the formula used or due to Lab space seems
moot....changing the formula to something like dE2000 is an easier
"fix" than changing to a Lab space that is more perceptually uniform.
my perceptually uniform 3 dE2000 worth. ;-)
Regards,
Terry
On Jul 16, 2009, at 1:14 PM, Robin Myers wrote:
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
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden