Integration with ITK

Overview

Code

C++

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

// SimpleITK includes
#include "SimpleITK.h"

// ITK includes
#include "itkImage.h"
#include "itkCurvatureFlowImageFilter.h"

// create convenient namespace alias
namespace sitk = itk::simple;

/**
 * This example shows how ITK and SimpleITK can be used together to work
 * on the same data. We use the same example application as the one presented
 * in the Segmentation/ConnectedThresholdImageFilter.cxx example, but we
 * replace the SimpleITK version of CurvatureFlowImageFilter with the
 * corresponding ITK version. While not terribly useful in this situation since
 * CurvatureFlowImageFilter is already available in SimpleITK this demonstrates
 * how ITK filters that have not been converted for SimpleITK can still be used
 * in a SimpleITK context
 */
int
main(int argc, char * argv[])
{

  //
  // Check command line parameters
  //
  if (argc < 7)
  {
    std::cerr << "Missing Parameters " << std::endl;
    std::cerr << "Usage: " << argv[0];
    std::cerr << " inputImage outputImage lowerThreshold upperThreshold "
                 "seedX seedY [seed2X seed2Y ... ]"
              << std::endl;
    return 1;
  }


  //
  // Read the image
  //
  sitk::ImageFileReader reader;
  reader.SetFileName(std::string(argv[1]));
  sitk::Image image = reader.Execute();


  //
  // Set up writer
  //
  sitk::ImageFileWriter writer;
  writer.SetFileName(std::string(argv[2]));

  //////
  // Blur using CurvatureFlowImageFilter
  //
  // Here we demonstrate the use of the ITK version of CurvatureFlowImageFilter
  // instead of the SimpleITK version.
  //////

  //
  // First, define the type alias that correspond to the types of the input
  // image. This requires foreknowledge of the data type of the input image.
  //
  const unsigned int Dimension = 2;
  using InternalPixelType = float;
  using InternalImageType = itk::Image<InternalPixelType, Dimension>;

  //
  // We must check the image dimension and the pixel type of the
  // SimpleITK image match the ITK image we will cast to.s
  //
  if (image.GetDimension() != Dimension)
  {
    std::cerr << "Input image is not a " << Dimension << " dimensional image as expected!" << std::endl;
    return 1;
  }

  //
  // The read sitk::Image could be any pixel type. Cast the image, to
  // float so we know what type we have.
  //
  sitk::CastImageFilter caster;
  caster.SetOutputPixelType(sitk::sitkFloat32);
  image = caster.Execute(image);

  //
  // Extract the itk image from the SimpleITK image
  //
  InternalImageType::Pointer itkImage = dynamic_cast<InternalImageType *>(image.GetITKBase());

  //
  // Always check the results of dynamic_casts
  //
  if (itkImage.IsNull())
  {
    std::cerr << "Unexpected error converting SimpleITK image to ITK image!" << std::endl;
    return 1;
  }

  //
  // Set up the blur filter and attach it to the pipeline.
  //
  using BlurFilterType = itk::CurvatureFlowImageFilter<InternalImageType, InternalImageType>;
  BlurFilterType::Pointer blurFilter = BlurFilterType::New();
  blurFilter->SetInput(itkImage);
  blurFilter->SetNumberOfIterations(5);
  blurFilter->SetTimeStep(0.125);


  //
  // Execute the  Blur pipeline by calling Update() on the blur filter.
  //
  blurFilter->Update();


  //
  // Return to the simpleITK setting by making a SimpleITK image using the
  // output of the blur filter.
  //
  sitk::Image blurredImage = sitk::Image(blurFilter->GetOutput());


  //////
  // Now that we have finished the ITK section, we return to the SimpleITK API
  //////


  //
  // Set up ConnectedThresholdImageFilter for segmentation
  //
  sitk::ConnectedThresholdImageFilter segmentationFilter;
  segmentationFilter.SetLower(atof(argv[3]));
  segmentationFilter.SetUpper(atof(argv[4]));
  segmentationFilter.SetReplaceValue(255);

  for (int i = 5; i + 1 < argc; i += 2)
  {
    std::vector<unsigned int> seed = { (unsigned int)atoi(argv[i]), (unsigned int)atoi(argv[i + 1]) };
    segmentationFilter.AddSeed(seed);
    std::cout << "Adding a seed at ";
    for (unsigned int j = 0; j < seed.size(); ++i)
    {
      std::cout << seed[j] << " ";
    }
    std::cout << std::endl;
  }

  sitk::Image outImage = segmentationFilter.Execute(blurredImage);


  //
  // Write out the resulting file
  //
  writer.Execute(outImage);

  return 0;
}