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From: "Steffen " <rileksn@gmail.com>
Newsgroups: comp.soft-sys.matlab
Subject: Image convolution, Fourier
Date: Tue, 29 Apr 2008 07:52:01 +0000 (UTC)
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Hi all,

I?m trying to get into the BLindDeconvolution of the
ImageProcessingToolbox and to do so I convolve a typical
image with a known gaussian PSF to see then whether the
algorithm returns a correct reconstructed PSF and image.
The problem is, that when I convolve the image using:

h = fspecial('gaussian',7,5); 
Blurred=conv2(image,h);

I always the this weird mesh grid in the Fouriertransform of
the image as shown in this image with a PSF of 13 pixels:
http://img153.imageshack.us/my.php?image=dcvpsf13wi4.jpg
Another example with a 5 pixel PSF: 
http://img501.imageshack.us/my.php?image=dcvpsf5vl6.jpg

The same occurs if I convolve the image using the imfilter
function. Is this periodic grid in the Blurred Fourier
(original image convolved with true PSF and it?s frequency)
an artefact or is there anything else I?m not aware of? I
could be wrong on this, but I?m pretty sure the grid
shouldn?t be there. Unfortunately it?s independent of the
image and just changes it?s appearance slightly with the PSF
applied. Any idea, advices, hints what went wrong??

Many thanks in advance and best regards,

Steffen