[Insight-users] Help with FFT in ITK

[Chris McIntosh]

Hello,

   I'm trying to perform an FFT in ITK, but I'm getting various problems. I 
have two different tries at creating the filters:


---------------
#include "itkVnlFFTComplexConjugateToRealImageFilter.h"
#include "itkVnlFFTRealToComplexConjugateImageFilter.h"
typedef itk::VnlFFTRealToComplexConjugateImageFilter<DataType,nDims> R2CType;
typename R2CType::Pointer R2C = R2CType::New();
typedef itk::VnlFFTComplexConjugateToRealImageFilter<DataType,nDims> C2RType;
typename C2RType::Pointer C2R = C2RType::New();
---------------

Or

--------------
#include "itkFFTWComplexConjugateToRealImageFilter.h"
#include "itkFFTWRealToComplexConjugateImageFilter.h"

typedef itk::FFTWRealToComplexConjugateImageFilter<DataType,nDims> R2CType;
typename R2CType::Pointer R2C = R2CType::New();
typedef itk::FFTWComplexConjugateToRealImageFilter<DataType,nDims> C2RType;
typename C2RType::Pointer C2R = C2RType::New();
---------------


I have built itk using the advanced option "use fftw", but I always get an 
error saying "FFTWReal...." not a member of itk namespace, when trying the 
second option.

If I use Vnl (which other e-mails to this group says I should avoid doing), it 
only seems to work for factorable image dimensions. An input of [12,12] works, 
but [12,13] gives an error. 

Does anybody know exactly I should go about getting fftw to work? Or, why Vnl 
is behaving as such?

-Chris