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Re: Image thresholding [message #15381 is a reply to message #15378]

Mon, 17 May 1999 00:00

David Kastrup
Messages: 33
Registered: February 1998

Member

David Brennan <9147261b@clinmed.gla.ac.uk> writes:

> Does anyone know of a fast routine or function for searching through a
> 3D data set and setting numbers within a predetermined range of values
> to zero. i.e,
>
> the range is 5 - 10
>
> A data set contains [0,1,2,3,4,5,6,7,8,9]. It becomes
> [0,1,2,3,4,0,0,0,0,0]

Well, in Matlab you would write

a(find(a >= 5 & a <= 10))=0;

The equivalent in IDL would be
a[where((a ge 5) and (a le 10))] = 0

Only that this fails miserably when no members satify the condition.
A typical case of idiotic semantics of IDL core functions. So we have
to write this as:

w = where((a ge 5) and (a le 10))
if w[0] ge 0 then a[w] = 0

--
David Kastrup Phone: +49-234-700-5570
Email: dak@neuroinformatik.ruhr-uni-bochum.de Fax: +49-234-709-4209
Institut fï¿½r Neuroinformatik, Universitï¿½tsstr. 150, 44780 Bochum, Germany

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		Re: Image thresholding By: David Kastrup on Mon, 17 May 1999 00:00
		Re: Image thresholding By: davidf on Mon, 17 May 1999 00:00
		Re: Image thresholding By: David Kastrup on Mon, 17 May 1999 00:00

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