Label Contours Of Connect Components

Synopsis

Label the contours of connected components.

Results

../../../../_images/LabelContoursOfConnectComponents.png

Generated Output.

Code

C++

#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkLabelContourImageFilter.h"
#include "itkConnectedComponentImageFilter.h"
#include "itkScalarToRGBColormapImageFilter.h"

#include "itksys/SystemTools.hxx"
#include <sstream>

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

namespace
{
using PixelType = unsigned char;
using RGBPixelType = itk::RGBPixel<unsigned char>;
using ImageType = itk::Image<PixelType, 2>;
using RGBImageType = itk::Image<RGBPixelType, 2>;
} // namespace

static void
CreateImage(ImageType::Pointer image);

int
main(int argc, char * argv[])
{
  // Create or read an image
  ImageType::Pointer image;
  if (argc < 2)
  {
    image = ImageType::New();
    CreateImage(image.GetPointer());
  }
  else
  {
    using ReaderType = itk::ImageFileReader<ImageType>;
    ReaderType::Pointer reader = ReaderType::New();
    reader->SetFileName(argv[1]);
    reader->Update();

    image = reader->GetOutput();
  }

  // Generate connected components
  using ConnectedComponentImageFilterType = itk::ConnectedComponentImageFilter<ImageType, ImageType>;
  ConnectedComponentImageFilterType::Pointer connectedComponentImageFilter = ConnectedComponentImageFilterType::New();
  connectedComponentImageFilter->SetInput(image);

  // Generate contours for each component
  using LabelContourImageFilterType = itk::LabelContourImageFilter<ImageType, ImageType>;
  LabelContourImageFilterType::Pointer labelContourImageFilter = LabelContourImageFilterType::New();
  labelContourImageFilter->SetInput(connectedComponentImageFilter->GetOutput());

  using RGBFilterType = itk::ScalarToRGBColormapImageFilter<ImageType, RGBImageType>;
  RGBFilterType::Pointer rgbFilter = RGBFilterType::New();
  rgbFilter->SetInput(labelContourImageFilter->GetOutput());
  rgbFilter->SetColormap(itk::RGBColormapFilterEnumType::Jet);

#ifdef ENABLE_QUICKVIEW
  QuickView viewer;
  viewer.AddImage(
    image.GetPointer(), true, argc > 1 ? itksys::SystemTools::GetFilenameName(argv[1]) : "Generated image");

  std::stringstream desc;
  desc << "LabelContourImageFilter";
  viewer.AddRGBImage(rgbFilter->GetOutput(), true, desc.str());

  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