Examples/Filtering/FFTDirectInverse2.cxx

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 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
 
#include "itkConfigure.h"
 
//
// This example is based on the on that was contributed by Stephan in the
// users list
//
//     http://public.kitware.com/pipermail/insight-users/2005-June/013482.html
//
//
 
// Software Guide : BeginLatex
//
// This example illustrates how to compute the direct Fourier transform
// followed by the inverse Fourier transform using the FFTW library.
//
// Software Guide : EndLatex
 
#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkResampleImageFilter.h"
#include "itkRescaleIntensityImageFilter.h"
#include "itkFFTWForwardFFTImageFilter.h"
#include "itkFFTWInverseFFTImageFilter.h"
#include "itkFlipImageFilter.h"
 
#if !defined(ITK_USE_FFTWF)
//#error "This example only works when single precision FFTW is used
// Changing WorkPixeltype to double and changing this conditional to
// ITK_USE_FFTWD will also work.
#endif
 
int
main(int argc, char * argv[])
{
  if (argc != 3)
  {
    std::cerr << "Usage: " << argv[0] << " input output" << std::endl;
    return EXIT_FAILURE;
  }
 
  // Software Guide : BeginLatex
  //
  // First we set up the types of the input and output images.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  constexpr unsigned int Dimension = 2;
  //  using OutputPixelType = unsigned char;
  using OutputPixelType = unsigned short;
  using WorkPixelType = float;
 
  using InputImageType = itk::Image<WorkPixelType, Dimension>;
  using WorkImageType = itk::Image<WorkPixelType, Dimension>;
  using OutputImageType = itk::Image<OutputPixelType, Dimension>;
  // Software Guide : EndCodeSnippet
 
  // File handling
  using ReaderType = itk::ImageFileReader<InputImageType>;
  using WriterType = itk::ImageFileWriter<OutputImageType>;
 
  ReaderType::Pointer inputreader = ReaderType::New();
  WriterType::Pointer writer = WriterType::New();
 
  inputreader->SetFileName(argv[1]);
  writer->SetFileName(argv[2]);
 
  // Read the image and get its size
  inputreader->Update();
 
  // Forward FFT filter
  using FFTFilterType = itk::FFTWForwardFFTImageFilter<InputImageType>;
 
  FFTFilterType::Pointer fftinput = FFTFilterType::New();
  fftinput->SetInput(inputreader->GetOutput());
  fftinput->Update();
 
  // This is the output type from the FFT filters
  using ComplexImageType = FFTFilterType::OutputImageType;
 
  // Do the inverse transform = forward transform + flip all axes
  using invFFTFilterType = itk::FFTWInverseFFTImageFilter<ComplexImageType>;
 
  invFFTFilterType::Pointer fftoutput = invFFTFilterType::New();
  fftoutput->SetInput(
    fftinput->GetOutput()); // try to recover the input image
  fftoutput->Update();
 
  // Rescale the output to suit the output image type
  using RescaleFilterType =
    itk::RescaleIntensityImageFilter<WorkImageType, OutputImageType>;
 
  RescaleFilterType::Pointer intensityrescaler = RescaleFilterType::New();
 
  std::cout << fftoutput->GetOutput()->GetLargestPossibleRegion().GetSize()
            << std::endl;
  intensityrescaler->SetInput(fftoutput->GetOutput());
 
  intensityrescaler->SetOutputMinimum(0);
  intensityrescaler->SetOutputMaximum(65535);
 
  // Write the output
  writer->SetInput(intensityrescaler->GetOutput());
  writer->Update();
 
  // DEBUG: std::cout << "inputreader
  // "<<inputreader->GetOutput()->GetLargestPossibleRegion().GetSize() <<
  // std::endl; DEBUG: std::cout << "fftinput "
  // <<fftinput->GetOutput()->GetLargestPossibleRegion().GetSize() <<
  // std::endl; DEBUG: std::cout << "fftoutput "
  // <<fftoutput->GetOutput()->GetLargestPossibleRegion().GetSize() <<
  // std::endl; DEBUG: std::cout << "intensityrescaller "
  // <<intensityrescaler->GetOutput()->GetLargestPossibleRegion().GetSize() <<
  // std::endl;
  return EXIT_SUCCESS;
}