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Congrid problem
- Subject: Congrid problem
- From: Jonathan Joseph <jj21(at)cornell.edu>
- Date: Fri, 23 Feb 2001 00:23:36 -0500
- Newsgroups: comp.lang.idl-pvwave
- Organization: Cornell University
- Sender: verified_for_usenet(at)cornell.edu (jj21 on baritone.tn.cornell.edu)
- Xref: news.doit.wisc.edu comp.lang.idl-pvwave:23620
I'm running IDL 5.3 on HP-UX and seeing the following
problem with congrid. I have a byte image that has large areas
of a particular solid color (a background color).
I rescale the image to be larger using congrid with the
/interp flag set. My nice solid areas of the background color,
which I would still expect to see unspoiled, now have artifacts
in them with value background_color - 1. This looks like a
bug. What's going on?
Here's an example that show's the problem:
IDL> a = bytarr(100,100) + 155b
IDL> b = congrid(a,140,140,/interp)
IDL> print, min(b), max(b)
154 155
IDL> w = where(b eq 154, count)
IDL> print,count
3703
IDL> tvscl, b eq 154 ;shows strange pattern of lines and dots
I would expect b in this example to be filled only with value 155.
Is this a bug or is there some other reason I am seeing this behavior?
BTW: I see the exact same behavior with INT instead of BYTE.
Thanks.
-Jonathan