[Insight-users] FFT

[Luis Ibanez]

Hi Alexandre,

I forgot to attach the images to my previous email  :-/

Please find them here.


   My apologies,


      Luis


-------------------
Luis Ibanez wrote:
> 
> Hi Alexandre,
> 
> 
>     It is *impossible* to try it all  :-)
> 
> 
> You may have tried many combinations,...
> 
> and
> certainly enough of them for generating frustration.
> 
> 
>     So... let's start from the beginning
> 
> 
> Take a deep breath and give us real technical
> information that we could use.
> 
> 
> 
> 1) You seem to have tried with the Circle.png file.
>    Did you used the command that I suggested in my
>    previous email ?:
> 
>     FFTImageFilter.exe
>       Insight/Examples/Data/Circle.png
>       circleReal.mhd
>       circleImg.mhd
> 
> 2) If it didn't work, then please tell us
>    How do you arrive to the conclusion that
>    it is not working.
> 
> 
>    a) Did it crashed ?
>    b) Did it throw an exception ?
>    c) Did it produced an empty image ?
> 
>    From your description it seems that it
>    is running and producing a:
> 
>          "The same results:
>           one level of grey scale"
> 
>     which lead us to think that what you
>     may have is a visualization issue.
> 
>     The FFT of a medical image will be typically
>     an image full of zeros, with a few non-zero
>     values concentrated in the corners.
> 
>     What are you using for visualizing the
>     output images ?
> 
>     What file format are you using for storing
>     the output image ?
> 
>     As an example of the correct output,
>     I'm attaching to this email the files
> 
>            circleReal.png
>            circleImg.png
> 
>     Please take a look at them and let us
>     know if they look like the ones you get.
> 
> 
> 3) For the record:
> 
>     Yes, you can convert your DICOM images
>     to PNG. but that's not the right solution
>     for your problem in this case. The input
>     file format, should be irrelevant here,
>     *as long* as you are declaring your image
>     to be of the correct pixel type.
> 
>     Tell us more about your DICOM image:
> 
>      - What is the image modality ?
>      - What is the Dimension ? (2D or 3D)
>      - How many pixels on each dimension ?
> 
> 
> 
>    Thanks
> 
> 
>       Luis
> 
> 
> --------------------------
> alexandre govignon wrote:
> 
>> i have done everything... s
>> o it's impossible with DICOM image? I think it's the reason why i am
>> not successful.
>>
>> I have tried all. The same results: one level of grey scale.
>>
>> But when i try with other type of image (circle .png), it still 
>> doesn't work
>>
>> The question is:
>>
>> Can i convert a DICOM to a png and a png to a DICOM?
>>
>> Do you think i can compute by my own a FFT on a DICOM image, thanks to
>> the developper's guide?
>>
>>
>>
>> 2008/4/3, Luis Ibanez <luis.ibanez at kitware.com>:
>>
>>> Hi Alexandre,
>>>
>>>
>>> 0) The fact that the image is being read
>>>   from a DICOM file format is irrelevant
>>>   for the purpose of computing an FFT.
>>>
>>>
>>> 1) Have you enabled FFTW ?
>>>
>>>
>>> 2) Have you run the examples:
>>>
>>>   Insight/Examples/Filtering/
>>>     FFTDirectInverse.cxx
>>>     FFTDirectInverse2.cxx
>>>     FFTImageFilter.cxx
>>>
>>>
>>> 3) In particular have you tried the following ?
>>>
>>> FFTImageFilter.exe
>>>   Insight/Examples/Data/Circle.png circleReal.mhd
>>> circleImg.mhd
>>>
>>>
>>>
>>> Please let us know,
>>>
>>>
>>>   Thanks
>>>
>>>
>>>      Luis
>>>
>>>
>>> ------------------------
>>>
>>> alexandre govignon wrote:
>>>
>>>
>>>> I would like to know if there is people who have succeed in fft with
>>>> ITK, because, i try a lot of things, but i think that it's really
>>>> impossible to make the FFT of a DICOM image in ITK...
>>>>
>>>>
>>>
>>
>>
> 
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