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Re: creating a 2D mask for image filtering [message #77291 is a reply to message #77215]

Thu, 18 August 2011 07:37

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Dave Higgins writes:

> Ah, yes, that is definitely better. The step-down is still smoothed out, but with better preservation of the central to-be-left-alone section.
>
> I had another idea, which was to plot concentric circles as seen in
> http://www.idlcoyote.com/tips/make_circle.html
> to approximate the filter shape a little better before smoothing, with the result that the smoothing needn't be as aggressive, and the central section is even better preserved.

And, you realize that this:

SHADE_SURF, filter*image

Is NOT how you apply this filter to an image, right?

The Hanning filter is a frequency domain filter and
it should be applied to the frequency image created
with the FFT function.

Since you were talking about "ringing" yesterday, I
thought you understood this, but this is the second
time I've seen a plot with "Filtered Image" as a
title and the *incorrect* filtered image. :-)

Cheers,

David

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

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[Message index]

		creating a 2D mask for image filtering By: David Higgins on Wed, 17 August 2011 03:47
		Re: creating a 2D mask for image filtering By: David Higgins on Thu, 18 August 2011 07:50
		Re: creating a 2D mask for image filtering By: orifox2003 on Wed, 20 February 2013 11:26
		Re: creating a 2D mask for image filtering By: David Fanning on Thu, 18 August 2011 07:37
		Re: creating a 2D mask for image filtering By: David Higgins on Thu, 18 August 2011 07:28
		Re: creating a 2D mask for image filtering By: David Fanning on Wed, 17 August 2011 10:44
		Re: creating a 2D mask for image filtering By: orifox2003 on Wed, 20 February 2013 11:30

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