Extract Boundaries Of Connected Regions In Binary Image

Synopsis

Extract the boundaries of connected regions in a binary image.

Results

../../../../_images/ExtractBoundariesOfConnectedRegionsInBinaryImage.png

Output In VTK Window

Code

C++

#include "itkImage.h"
#include "itkImageFileWriter.h"
#include "itkBinaryContourImageFilter.h"

#ifdef ENABLE_QUICKVIEW
#  include "QuickView.h"
#endif

using ImageType = itk::Image<unsigned char, 2>;

static void
CreateImage(ImageType::Pointer image);

int
main(int, char *[])
{
  ImageType::Pointer image = ImageType::New();
  CreateImage(image);

  using binaryContourImageFilterType = itk::BinaryContourImageFilter<ImageType, ImageType>;

  binaryContourImageFilterType::Pointer binaryContourFilter = binaryContourImageFilterType::New();
  binaryContourFilter->SetInput(image);

#ifdef ENABLE_QUICKVIEW
  QuickView viewer;
  viewer.AddImage<ImageType>(image);
  viewer.AddImage<ImageType>(binaryContourFilter->GetOutput());
  viewer.Visualize();
#endif
  return EXIT_SUCCESS;
}

void
CreateImage(ImageType::Pointer image)
{
  // Create an image with 2 connected components
  ImageType::RegionType region;
  ImageType::IndexType  start;
  start[0] = 0;
  start[1] = 0;

  ImageType::SizeType size;
  unsigned int        NumRows = 200;
  unsigned int        NumCols = 300;
  size[0] = NumRows;
  size[1] = NumCols;

  region.SetSize(size);
  region.SetIndex(start);

  image->SetRegions(region);
  image->Allocate();

  // Make a square
  for (unsigned int r = 20; r < 80; r++)
  {
    for (unsigned int c = 30; c < 100; c++)
    {
      ImageType::IndexType pixelIndex;
      pixelIndex[0] = r;
      pixelIndex[1] = c;

      image->SetPixel(pixelIndex, 255);
    }
  }

  // Make another square
  for (unsigned int r = 100; r < 130; r++)
  {
    for (unsigned int c = 115; c < 160; c++)
    {
      ImageType::IndexType pixelIndex;
      pixelIndex[0] = r;
      pixelIndex[1] = c;

      image->SetPixel(pixelIndex, 255);
    }
  }
}

Classes demonstrated