ITK/Examples/SpectralAnalysis/CrossCorrelationInFourierDomain

CrossCorrelationInFourierDomain.cxx

<source lang="cpp">

1. include "itkImage.h"
2. include "itkImageFileReader.h"
3. include "itkImageFileWriter.h"

1. include "itkVnlFFTRealToComplexConjugateImageFilter.h"
2. include "itkVnlFFTComplexConjugateToRealImageFilter.h"
3. include "itkComplexToRealImageFilter.h"
4. include "itkComplexToImaginaryImageFilter.h"
5. include "itkRealAndImaginaryToComplexImageFilter.h"
6. include "itkMultiplyByConstantImageFilter.h"
7. include "itkMultiplyImageFilter.h"
8. include "itkRescaleIntensityImageFilter.h"
9. include "itkFFTShiftImageFilter.h"

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

 const    unsigned int    Dimension = 2;
 typedef  float           PixelType;
 typedef itk::Image< PixelType, Dimension >  ImageType;

 if( argc < 3 )
   {
   std::cerr << "Missing Parameters " << std::endl;
   std::cerr << "Usage: " << argv[0];
   std::cerr << " FixedImage MovingImage"<< std::endl;;
   return EXIT_FAILURE;
   }
 std::string fixedImageFilename = argv[1];
 std::string movingImageFilename = argv[2];

 // Read the input images
 typedef itk::ImageFileReader< ImageType  > ImageReaderType;
 ImageReaderType::Pointer  fixedImageReader  = ImageReaderType::New();
 fixedImageReader->SetFileName( fixedImageFilename );
 fixedImageReader->Update();
 
 ImageReaderType::Pointer movingImageReader = ImageReaderType::New();
 movingImageReader->SetFileName( movingImageFilename );
 movingImageReader->Update();

 // Shift the input images
 typedef itk::FFTShiftImageFilter< ImageType, ImageType > FFTShiftFilterType;
 FFTShiftFilterType::Pointer fixedFFTShiftFilter = FFTShiftFilterType::New();
 fixedFFTShiftFilter->SetInput(fixedImageReader->GetOutput());
 fixedFFTShiftFilter->Update();

 FFTShiftFilterType::Pointer movingFFTShiftFilter = FFTShiftFilterType::New();
 movingFFTShiftFilter->SetInput(movingImageReader->GetOutput());
 movingFFTShiftFilter->Update();
 
 // Compute the FFT of the input
 typedef itk::VnlFFTRealToComplexConjugateImageFilter<
                               PixelType, Dimension >  FFTFilterType;
 FFTFilterType::Pointer fixedFFTFilter = FFTFilterType::New();
 fixedFFTFilter->SetInput( fixedFFTShiftFilter->GetOutput() );
 fixedFFTFilter->Update();
 
 FFTFilterType::Pointer movingFFTFilter = FFTFilterType::New();
 movingFFTFilter->SetInput( movingFFTShiftFilter->GetOutput() );
 
 typedef FFTFilterType::OutputImageType    SpectralImageType;

 // Take the conjugate of the fftFilterMoving
 // Extract the real part
 typedef itk::ComplexToRealImageFilter<SpectralImageType, ImageType> RealFilterType;
 RealFilterType::Pointer realFilter = RealFilterType::New();
 realFilter->SetInput(movingFFTFilter->GetOutput());

 // Extract the imaginary part
 typedef itk::ComplexToImaginaryImageFilter<SpectralImageType, ImageType> ImaginaryFilterType;
 ImaginaryFilterType::Pointer imaginaryFilter = ImaginaryFilterType::New();
 imaginaryFilter->SetInput(movingFFTFilter->GetOutput());

 // Flip the sign of the imaginary and combine with the real part again
 typedef itk::MultiplyByConstantImageFilter<ImageType,PixelType,ImageType> MultiplyConstantFilterType;
 MultiplyConstantFilterType::Pointer flipSignFilter = MultiplyConstantFilterType::New();
 flipSignFilter->SetConstant(-1);
 flipSignFilter->SetInput(imaginaryFilter->GetOutput());
 typedef itk::RealAndImaginaryToComplexImageFilter<PixelType,PixelType,PixelType,2> RealImagToComplexFilterType;
 RealImagToComplexFilterType::Pointer conjugateFilter = RealImagToComplexFilterType::New();
 conjugateFilter->SetInput1(realFilter->GetOutput());
 conjugateFilter->SetInput2(flipSignFilter->GetOutput());

 // The conjugate product of the spectrum
 typedef itk::MultiplyImageFilter< SpectralImageType,
                                 SpectralImageType,
                                 SpectralImageType >  MultiplyFilterType;
 MultiplyFilterType::Pointer multiplyFilter = MultiplyFilterType::New();
 multiplyFilter->SetInput1( fixedFFTFilter->GetOutput() );
 multiplyFilter->SetInput2( conjugateFilter->GetOutput() );

 // IFFT
 typedef itk::VnlFFTComplexConjugateToRealImageFilter<
       PixelType, Dimension >  IFFTFilterType;
 IFFTFilterType::Pointer fftInverseFilter = IFFTFilterType::New();
 fftInverseFilter->SetInput( multiplyFilter->GetOutput() );

 // Write the spectrum
 typedef unsigned char OutputPixelType;
 typedef itk::Image< OutputPixelType, Dimension > OutputImageType;
 typedef itk::RescaleIntensityImageFilter< ImageType,  OutputImageType > RescaleFilterType;
 typedef itk::ImageFileWriter< OutputImageType >  WriterType;
 RescaleFilterType::Pointer  rescaler =  RescaleFilterType::New();
 WriterType::Pointer writer =  WriterType::New();
 writer->SetFileName( "CrossCorr.png" );
 rescaler->SetInput( fftInverseFilter->GetOutput() );
 rescaler->SetOutputMinimum(0);
 rescaler->SetOutputMaximum(255);
 writer->SetInput( rescaler->GetOutput() );
 writer->Update();

 return EXIT_SUCCESS;

} </source>

CMakeLists.txt

<source lang="cmake"> cmake_minimum_required(VERSION 2.6)

project(CrossCorrelationInFourierDomain)

find_package(ITK REQUIRED) include(${ITK_USE_FILE})

add_executable(CrossCorrelationInFourierDomain CrossCorrelationInFourierDomain.cxx ) target_link_libraries(CrossCorrelationInFourierDomain ITKIO ITKCommon) </source>