[Insight-users] Fwd: FFT

[alexandre govignon]

Fot the image i have no website, sorry... But it's just one colored
(grey) image.

---------- Forwarded message ----------
From: alexandre govignon <govignon.alexandre at gmail.com>
Date: 28 mars 2008 16:20
Subject: Re: [Insight-users] FFT
To: Luis Ibanez <luis.ibanez at kitware.com>, insight-users at itk.org


Hi Luis,
 Thanks for reply,
 VnlFFT and FFTW have the same following in code, except replace
 itkVnlFFT by itkFFTW


 My code with VNL is:

 #if defined(_MSC_VER)
 #pragma warning ( disable : 4786 )
 #endif

 #ifdef __BORLANDC__
 #define ITK_LEAN_AND_MEAN
 #endif


 // Software Guide : BeginCodeSnippet
 #include "itkImage.h"

 #include "itkImageFileReader.h"
 #include "itkImageFileWriter.h"

 #include "itkVnlFFTRealToComplexConjugateImageFilter.h"

 #include "itkComplexToRealImageFilter.h"
 #include "itkComplexToImaginaryImageFilter.h"

 #include "itkRescaleIntensityImageFilter.h"

 #include <iostream>



 int main(int argc, char * argv[])
 {


  // FFT



    if( argc < 3 )
    {
        std::cerr << "Usage: " << argv[0] << " inputScalarImage
 outputRealPartOfComplexImage outputRealImaginaryPartOfComplexImage" <<
 std::endl;
    }




  typedef float PixelType;

  const unsigned int Dimension = 2;

  typedef itk::Image< PixelType, Dimension > ImageType;


  typedef itk::FFTRealToComplexConjugateImageFilter< PixelType,
 Dimension > FFTFilterType;    //Filtre FFT r√(c)el √† complexe
 conjugu√(c)

  FFTFilterType::Pointer fftFilter = FFTFilterType::New();    //
 instanciation Filtre FFT



  typedef itk::ImageFileReader< ImageType > ReaderType;

  ReaderType::Pointer reader = ReaderType::New();

  reader->SetFileName( argv[1] );



  fftFilter->SetInput( reader->GetOutput() );
  try
    {

        fftFilter->Update();

    }

    catch( itk::ExceptionObject & excp )
    {

        std::cerr << "Error: " << std::endl;
        std::cerr << excp << std::endl;
        return EXIT_FAILURE;

    }



    typedef FFTFilterType::OutputImageType ComplexImageType;


    typedef itk::ImageFileWriter< ComplexImageType > ComplexWriterType;

    ComplexWriterType::Pointer complexWriter = ComplexWriterType::New();

    complexWriter->SetFileName("complexImage.mhd");

    complexWriter->SetInput( fftFilter->GetOutput() );



    try
    {

        complexWriter->Update();

    }

    catch( itk::ExceptionObject & excp )
    {

        std::cerr << "Error: " << std::endl;
        std::cerr << excp << std::endl;
        return EXIT_FAILURE;

    }


    typedef itk::ComplexToRealImageFilter< ComplexImageType, ImageType
 > RealFilterType;

    RealFilterType::Pointer realFilter = RealFilterType::New();

    realFilter->SetInput( fftFilter->GetOutput() );


    typedef unsigned char WritePixelType;

    typedef itk::Image< WritePixelType, Dimension > WriteImageType;



    typedef itk::RescaleIntensityImageFilter<ImageType, WriteImageType
 > RescaleFilterType;        // on d√(c)clare le r√(c)echelonnage

    RescaleFilterType::Pointer intensityRescaler =
 RescaleFilterType::New();                    // instanciation du
 pointeur sur le r√(c)echelonneur

    intensityRescaler->SetInput( realFilter->GetOutput() );

    intensityRescaler->SetOutputMinimum( 0 );

    intensityRescaler->SetOutputMaximum( 255 );

    typedef itk::ImageFileWriter< WriteImageType > WriterType;

    WriterType::Pointer writer = WriterType::New();

    writer->SetFileName( argv[2] );

    writer->SetInput( intensityRescaler->GetOutput() );

    try
    {

        writer->Update();

    }

    catch( itk::ExceptionObject & excp )
    {

        std::cerr << "Error writing the real image: " << std::endl;
        std::cerr << excp << std::endl;
        return EXIT_FAILURE;
    }

  return EXIT_SUCCESS;

 }



 Regards,
 Alexandre



 2008/3/28, Luis Ibanez <luis.ibanez at kitware.com>:

>
 >  Hi Alexandre,
 >
 >  Have you tried the follwing examples ?
 >
 >
 >     Insight/Examples/Filtering/
 >               FFTDirectInverse.cxx
 >               FFTDirectInverse2.cxx
 >               FFTImageFilter.cxx
 >               FFTImageFilterFourierDomainFiltering.cxx
 >
 >  They contribute three tests to the Nightly Dashboards.
 >
 >
 >  --
 >
 >
 >  Can you post to the list the code that you are currently using ?
 >
 >  Can you post in a public web site one of the typical images
 >  that you want to process ?
 >
 >
 >     Please let us know,
 >
 >
 >         Thanks
 >
 >
 >            Luis
 >
 >
 >  -------------------------
 >
 > alexandre govignon wrote:
 >  > I am desperate, i m trying to make a FFT and it doesn't work. I have
 >  > tried is the same as the beginning. I obtained image in one scale of
 >  > grey with VnlFFT and with FFTW. Moreover FFTW transform square image in
 >  > rectangular image. Are there anybody who can help me?
 >  >
 >  > --
 >  > Cordialement,
 >  > Alexandre Govignon.
 >  >
 >  >
 >
 > > ------------------------------------------------------------------------
 >  >
 >  > _______________________________________________
 >  > Insight-users mailing list
 >  > Insight-users at itk.org
 >  > http://www.itk.org/mailman/listinfo/insight-users
 >


-- 
Cordialement,
Alexandre Govignon.