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Re: Curve Fitting Question [message #82112 is a reply to message #82001]

Tue, 20 November 2012 06:22

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

David Fanning writes:

> Yes, this Otsu's thresholding function works great. It
> didn't have quite as many features as I would have liked,
> so I stole the main ideas and wrote up a similar program
> that is working very, very well with the data sets I
> am working with today. It even picks reasonable
> thresholds when the dividing line between pixel
> populations is not totally straightforward. Thanks
> for bringing it to my attention.
>
> You can find my version of the program here:
>
> http://www.idlcoyote.com/programs/cgotsu_threshold.pro

Hold off on this a minute. I've been using my version
of the OTSU_THRESHOLD program for a week now, and I've
been seeing some strange results. The only thing I did
in my program was to beef up the keywords and error handling
for the histogram itself. I didn't change the underlying
code for OTSU_THRESHOLD.

In fact, just to confirm this, I've now gone back and
used the VERY same variable names, etc. But, I seem
to be getting different slightly different results with
the two programs.

I am trying to track this down now. In fact, I'm using the
newsgroup in EXACTLY the way Helder describes this morning!

Here is what just occurred to me. One of the things I am
VERY particular about (long experience, probably) is matching
the data type of the BINSIZE keyword with the data type of
the data going into the histogram. The OTSU_THRESHOLD program
I was using as a model didn't do this. I wonder if this is
the source of the difference. Back soon! :-)

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")

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[Message index]

		Curve Fitting Question By: ftdwh on Tue, 14 September 1993 11:01
		Re: Curve Fitting Question By: David Fanning on Tue, 13 November 2012 15:24
		Re: Curve Fitting Question By: cgguido on Wed, 14 November 2012 06:22
		Re: Curve Fitting Question By: David Fanning on Tue, 20 November 2012 06:22
		Re: Curve Fitting Question By: Mark Piper on Tue, 13 November 2012 08:31
		Re: Curve Fitting Question By: David Fanning on Mon, 12 November 2012 19:40
		Re: Curve Fitting Question By: ben.bighair on Mon, 12 November 2012 18:47
		Re: Curve Fitting Question By: David Fanning on Mon, 12 November 2012 17:23
		Re: Curve Fitting Question By: David Fanning on Mon, 12 November 2012 17:18
		Re: Curve Fitting Question By: Craig Markwardt on Mon, 12 November 2012 15:51
		Re: Curve Fitting Question By: David Fanning on Tue, 20 November 2012 06:58

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