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Re: Congrid problem [message #23854 is a reply to message #23853]

Fri, 23 February 2001 06:13

Paul van Delst
Messages: 364
Registered: March 1997

Senior Member

Jonathan Joseph wrote:
>
> 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

IDL> print, !version
{ x86 linux unix 5.4.1 Jan 16 2001 32 32}
IDL> a = bytarr(100,100) + 155b
IDL> b = congrid(a,140,140,/interp)
% Compiled module: CONGRID.
IDL> print, min(b), max(b)
155 155
IDL> w = where(b eq 154, count)
IDL> print,count
0

--
Paul van Delst A little learning is a dangerous thing;
CIMSS @ NOAA/NCEP Drink deep, or taste not the Pierian spring;
Ph: (301)763-8000 x7274 There shallow draughts intoxicate the brain,
Fax:(301)763-8545 And drinking largely sobers us again.
pvandelst@ncep.noaa.gov Alexander Pope.

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[Message index]

		Re: Congrid problem By: pit on Fri, 23 February 2001 09:03
		Re: Congrid problem By: Alex Schuster on Fri, 23 February 2001 06:43
		Re: Congrid problem By: Jaco van Gorkom on Fri, 23 February 2001 06:32
		Re: Congrid problem By: Paul van Delst on Fri, 23 February 2001 06:13
		Re: Congrid problem By: Craig Markwardt on Fri, 23 February 2001 05:53

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