Summary:
Similarly to the fftshift and ifftshift functions of Matlab, this filter swaps the "half-spaces" of the input image along each dimension.

Evidence:
The author provides two input images and their corresponding outputs using or not the "inverse" option.

Open Science:
The author provides the source code and an example to reproduce his experiments. He also provides the images.

Reproducibility:
I compiled the code using CMake 2.4 and Visual C++ 2005 Express on Windows XP SP2, there is no error or warning. I ran it with different types of image supported by ITK (png, jpg, tiff, gif, 24-bit bitmap) and it works great.
The results are easily reproducible with the information from the paper.

Use of Open Source Software:
The authors use ITK.

Open Source Contributions:
The author provides his source code and describes clearly how to use it.

Code Quality:
The code is easy to read and all the necessary comments are presents.

Requests for additional information from authors:
Maybe the author could shortly describe how the filter puts the zero-frequency component in the center of the image (swapping parts of the image) in the pdf file.

Summary:
fftshift is a common operation to visualise fourier-transformed image. This contribution presents a new filter that performs this operation.

Hypothesis:
N/A

Evidence:
Author states that this is a common operation which is missing in ITK - this is obviously true.

Open Science:
Do the authors provide the source code of the programs used in their experiments? YES
Do the authors provide the input images that they used? YES
Or are those images publicly available? N/A
Do the authors provide the output images that they show in the paper? YES
Do the authors provide enough details for you to be able to replicate their work? YES

Reproducibility:
Did you reproduce the authors’ work? YES
Did you download their code? Did you compile it? Did you run it? YES/YES/YES
Did you managed to get the same results that they reported? YES
Were there information missing from the paper, that was necessary for you to reproduce the work? NO
Suggest improvements that will make easier for future readers to reproduce this work. not necessary

Use of Open Source Software:
ITK/CMake

Open Source Contributions:
Do the author’s provide their source code? YES
Is it in a form that is usable? YES
Do they describe clearly how to use of the code? YES
How long did it take you to use that code? few seconds

Code Quality:
Was the code easy to read? YES
Did they use a modern coding style? YES
Did they rely on non-portable mechanism? NO
Was it suitable for multiple-platforms? YES

Applicability to other problems:
N/A

Suggestions for future work & comments:
I tried to validate the output - i executed the test code on BrainProtonDensitySliceBorder20.png image from ITK examples data set and then tried to compare the results (forward and inverse) with results of matlab fftshift function.

I discovered, that the forward run (3. parameter==0 on commandline) of this code does what does the ifftshift function of matlab and the inverse run (3. parameter==1) has the same result as fftshift function.

I suppose to author to check if i am true and possibly switch the forward/inverse behavior to let the functionality match with the matlab.