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Congrid problem [message #23858]

Thu, 22 February 2001 21:23

Jonathan Joseph
Messages: 69
Registered: September 1998

Member

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

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[Message index]

		Congrid problem By: Jonathan Joseph on Thu, 22 February 2001 21:23
		Re: Congrid problem By: Nigel Wade on Tue, 27 February 2001 02:17
		Re: Congrid problem By: Jeff Kolthammer on Mon, 26 February 2001 10:53

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