[Insight-users] pb with FFTDirectInverse.cxx

[Renaud Isabelle]

Hi,
 
I tried to apply your example about using FFT. It works well, actually. 
 
However, it seems to have something wrong with the regression. 
 
To apply the FFT, each dimension of the input image should be a multiple of 2, right? 
 
In one of my test image, it seems that the regression will find 2048 as the nearest multiple of 2 of my real dimension 1024. Is it correct? What not use 1024 instead? 
 
here is the code:
 
int n=0;
worksize[0] = inputsize[0]; //inputsize[0] = 1024
while(worksize[i] >> = 1) n++;
worksize[0] = 1 << (n+1); //worksize[0] = 2048
 
Isabelle
 


Luis Ibanez <luis.ibanez at kitware.com> a écrit :

Hi Isabelle,

You can get the examples from the Web CVS portal.

http://www.itk.org/cgi-bin/viewcvs.cgi/?cvsroot=Insight


Note that CVS access is a fundamental need for
participating of an Open Source community.

I would *strongly* encourage you to expose your institution
to the importance of CVS and how it enables you to take
advantage of the abundant free resources the Open Source
movement is making available.

If you oppose resistance from stubborn or retrograde
system administrators that are fearful of opening
CVS ports in a firewall, then please let us know,
we will be glad of helping you educate your system
administrator.



Best regards,



Luis




-----------------------
Renaud Isabelle wrote:

> Hi Luis,
> 
> Thanks for helping me.
> 
> I can have access to the ITKsoftware but I don't have CVS installed on 
> my computer. Is it possible to you to send me?
> 
> Isabelle
> 
> 
> 
> */Luis Ibanez /* a écrit :
> 
> 
> Hi Isabelle,
> 
> 
> You will find an example on Fourier Domain filtering
> in the ITK Software Guide
> 
> 
> http://www.itk.org/ItkSoftwareGuide.pdf
> 
> 
> In Section 6.10 "Frequency Domain", pdf-page 279.
> 
> The corresponding source code examples are
> available in the directory:
> 
> 
> Insight/Examples/Filtering
> 
> 
> Note that those examples are recent, so you will
> have to use a CVS checkout of ITK in order to
> find them.
> 
> 
> 
> Regards,
> 
> 
> Luis
> 
> 
> 
> -----------------------
> Renaud Isabelle wrote:
> 
> > Hi Remi,
> >
> > Sorry to bother you. I see your posted email to insight-users
> list about
> > how to compute FFT and delete some frequencies.
> >
> > This is exactly what I have to do now. I have to compute FFT of each
> > lign of my 2D image and then, delete negative frequencie! s. But
> I don't
> > know how to do it. Can you advice me? I'm really lost.
> >
> > Thanks for help,
> >
> > Isabelle
> >
> > remi.charrier at cpe.fr
> >
> > /Wed Apr 13 17:39:34 EDT 2005/
> >
> >
> ------------------------------------------------------------------------
> >
> > hi all,
> > I try to use the itk FFT and its inverse to delete some
> frequencies in an
> > image
> > but the itk filters seem to not work.
> > To know what is not working, I tried to apply the FFT to my image
> and just
> > after I apply the FFT inverse to the result. It should give me
> the same image
> > than the initial one, but it does not.
> > I am using
> > #include "itkVnlFFTRealToComplexConjugateImageFilter.h"
> > and
> > #include "itkVnlFFTComplexConjugateToRealImageFilter.h"
> > Does some! one know why it is not working or what I should do to
> make it work?
> >
> > Thanks
> > remi charrier
> >
> >
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> >
> >
> >
> ------------------------------------------------------------------------
> >
> > _______________________________________________
> > Insight-users mailing list
> > Insight-users at itk.org
> > http://www.itk.org/mailman/listinfo/insight-users
> 
> 
> 
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> 




		
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