Re: Color Measurement
Re: Color Measurement
- Subject: Re: Color Measurement
- From: "Fleisher, Ken" <email@hidden>
- Date: Wed, 15 Jul 2009 17:05:41 -0400
- Thread-topic: Color Measurement
On 7/15/09 4:52 PM, "Fleisher, Ken" <email@hidden> wrote:
> (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
> Weber¹s Law of Just Noticeable Difference, a JND is the ³smallest detectable
> difference between a starting and secondary level of a particular sensory
> stimulus.²
Another way to state the definition of a JND, which is also known as a
difference threshold, is ³the amount of change in stimulus energy required
to produce a just noticeable difference (jnd) in sensation.²
The first definition I quoted above is generally correct, but it was taken
from a paraphrasing on Wikipedia
<http://en.wikipedia.org/wiki/Difference_limen > which lists
<http://www.usd.edu/psyc301/WebersLaw.htm > as the source. Since it was
quoted, I did not realize it was a paraphrase and I have once again learned
my lesson on even looking at Wikipedia! Again, the definition is not
incorrect, but it¹s just not directly quoted from Weber¹s Law as it seemed
while reading it.
The second definition is quoted from the instructor¹s lecture notes from my
course in Vision and Psychophysics. I¹m sure that once I get home I can
actually look up more exact wording directly from Weber, but I don¹t think
that¹s necessary...
--
Kenneth N. Fleisher
Photographer
Imaging & Visual Services
National Gallery of Art
6th Street & Constitution Avenue, N.W.
Washington, D.C. 20565
Phone: (202) 712-7471
email@hidden
Mailing Address:
2000B South Club Drive
Landover, MD 20785
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