[Numpy-discussion] fft help

Torgil Svensson torgil.svensson at gmail.com
Thu Dec 29 10:21:46 EST 2011

This is because fft computes one-dimensional transforms (on each row).
Try fft2 instead.


fft(a, n=None, axis=-1)
    Compute the one-dimensional discrete Fourier Transform.

fft2(a, s=None, axes=(-2, -1))
    Compute the 2-dimensional discrete Fourier Transform

fftn(a, s=None, axes=None)
    Compute the N-dimensional discrete Fourier Transform.

On Wed, Dec 28, 2011 at 10:05 PM, Burlen Loring <burlen.loring at gmail.com> wrote:
> Hi
> I have an image I need to do an fft on, I tried numpy.fft but results are
> not what I expected, and differ from matlab.
> My input image is a weird size, 5118x1279, I think numpy fft is not liking it. In
> numpy the fft appears to be computed multiple times and tiled across the
> output image. In other words the pattern I see in matlab fft is tiled
> repeatedly over numpy fft output. Any idea on what I'm doing wrong?
> you can see repeated pattern in the top panel of this image which also has
> the input in the bottom panel.
> http://old.nabble.com/file/p33047057/fft_uex.png  fft_uex.png
> tx
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