WikiExamples/Segmentation/ContourExtractor2DImageFilter.cxx

#include "itkImage.h"
#include "itkImageFileWriter.h"
#include "itkContourExtractor2DImageFilter.h"
#include "itkApproximateSignedDistanceMapImageFilter.h"

using UnsignedCharImageType = itk::Image<unsigned char, 2>;
using FloatImageType = itk::Image<float, 2>;
 
static void CreateImage(UnsignedCharImageType::Pointer image);
 
int main(int, char *[])
{
  UnsignedCharImageType::Pointer image = UnsignedCharImageType::New();
  CreateImage(image);
 
  using ApproximateSignedDistanceMapImageFilterType = itk::ApproximateSignedDistanceMapImageFilter< UnsignedCharImageType, FloatImageType  >;
  ApproximateSignedDistanceMapImageFilterType::Pointer approximateSignedDistanceMapImageFilter = ApproximateSignedDistanceMapImageFilterType::New();
  approximateSignedDistanceMapImageFilter->SetInput(image);
  approximateSignedDistanceMapImageFilter->SetInsideValue(255);
  approximateSignedDistanceMapImageFilter->SetOutsideValue(0);
  approximateSignedDistanceMapImageFilter->Update();
  
  using ContourExtractor2DImageFilterType = itk::ContourExtractor2DImageFilter <FloatImageType>;
  ContourExtractor2DImageFilterType::Pointer contourExtractor2DImageFilter
          = ContourExtractor2DImageFilterType::New();
  contourExtractor2DImageFilter->SetInput(approximateSignedDistanceMapImageFilter->GetOutput());
  contourExtractor2DImageFilter->SetContourValue(0);
  contourExtractor2DImageFilter->Update();
  
  std::cout << "There are " << contourExtractor2DImageFilter->GetNumberOfOutputs() << " contours" << std::endl;
 
 
  for(unsigned int i = 0; i < contourExtractor2DImageFilter->GetNumberOfOutputs(); ++i)
    {
    std::cout << "Contour " << i << ": " << std::endl;
    ContourExtractor2DImageFilterType::VertexListType::ConstIterator vertexIterator = 
      contourExtractor2DImageFilter->GetOutput(i)->GetVertexList()->Begin();
    while(vertexIterator != contourExtractor2DImageFilter->GetOutput(i)->GetVertexList()->End())
      {
      std::cout << vertexIterator->Value() << std::endl;
      ++vertexIterator;
      }
    std::cout << std::endl;
    }

  return EXIT_SUCCESS;
}
 
void CreateImage(UnsignedCharImageType::Pointer image)
{
  // Create an image
  itk::Index<2> start;
  start.Fill(0);
 
  itk::Size<2> size;
  size.Fill(100);
 
  itk::ImageRegion<2> region(start, size);
  image->SetRegions(region);
  image->Allocate();
  image->FillBuffer(0);
 
  // Create a line of white pixels
  for(unsigned int i = 40; i < 60; ++i)
    {
    itk::Index<2> pixel;
    pixel.Fill(i);
    image->SetPixel(pixel, 255);
    }
    
  // Create another line of pixels
  for(unsigned int i = 10; i < 20; ++i)
    {
    itk::Index<2> pixel;
    pixel[0] = 10;
    pixel[1] = i;
    image->SetPixel(pixel, 255);
    }
 
  using WriterType = itk::ImageFileWriter< UnsignedCharImageType  >;
  WriterType::Pointer writer = WriterType::New();
  writer->SetFileName("image.png");
  writer->SetInput(image);
  writer->Update();
}