[Numpy-discussion] strange behavior convolving via fft
Mon May 11 15:15:18 CDT 2009
Did I pad my example incorrectly? Both images were upped to the larger
nearest power of 2 (256)...
Does the scipy implementation do this differently? I thought that since FFTW
support has been dropped, that scipy and numpy use the same routines...
2009/5/11 Stéfan van der Walt <email@example.com>
> Hi Chris
> 2009/5/11 Chris Colbert <firstname.lastname@example.org>:
> > When convolving an image with a large kernel, its know that its faster to
> > perform the operation as multiplication in the frequency domain. The
> > code example shows that the results of my 2d filtering are shifted from
> > expected value a distance 1/2 the width of the filter in both the x and y
> > directions. Can anyone explain why this occurs? I have been able to find
> > answer in any of my image processing books.
> Just as a reminder, when doing this kind of filtering always pad
> correctly. Scipy does this in
> I've also got some filtering implemented in
> Numpy-discussion mailing list
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