Re: Color Measurement
Re: Color Measurement
- Subject: Re: Color Measurement
- From: Richard Baguley <email@hidden>
- Date: Wed, 15 Jul 2009 17:07:39 -0400
This is not correct. The JND is just as Robin Meyers described it. The
difference with dE 2000 and the original dE 1976 is that the former
attempts to make the color space of the latter more visually uniform. In
other words, in dE 1976, dE 3 would mean a different amount of perceived
change depending on which color is being viewed. This is because the
L*a*b* color space is visually non-uniform, or said another way it is
not a Euclidean space. DE 2000 attempts to correct this problem and is a
great improvement, but is still not a perfect solution. One unfortunate
aspect of dE 2000 is that it was scaled differently and produces smaller
numbers than dE 1976 which is why the JND is a smaller number.
Ah, I stand corrected.
(although, of course there is no precise definition of what
JND really means...)
Why do you think that? Of course there is a precise definition for JND.
From Weber’s Law of Just Noticeable Difference, a JND is the “smallest
detectable difference between a starting and secondary level of a
particular sensory stimulus.”
Yes, but the JND will depend on the sensitivity of the measuring device,
which is *extremely* variable when you are dealing with the human eye.
My right eye, for instance, seems to be significantly better at
detecting color differences than my left from my tests. That's more what
I meant: JND is a statistical construct, not an absolute quantity.
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