WikiExamples/Statistics/ScalarImageKmeansImageFilter.cxx

#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkScalarImageKmeansImageFilter.h"
#include "itkRelabelComponentImageFilter.h"
#include "itkRescaleIntensityImageFilter.h"
#include "itkImageRegionIterator.h"

#include <itkImageToVTKImageFilter.h>

#include "vtkVersion.h"
#include "vtkImageViewer.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkSmartPointer.h"
#include "vtkImageActor.h"
#include "vtkImageMapper3D.h"
#include "vtkInteractorStyleImage.h"
#include "vtkRenderer.h"

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 KMeansFilterType = itk::ScalarImageKmeansImageFilter< ImageType >;

  KMeansFilterType::Pointer kmeansFilter = KMeansFilterType::New();

  kmeansFilter->SetInput(image);
  kmeansFilter->SetUseNonContiguousLabels(true);
  kmeansFilter->AddClassWithInitialMean(8);
  kmeansFilter->AddClassWithInitialMean(110);
  kmeansFilter->AddClassWithInitialMean(210);
  kmeansFilter->Update();

  KMeansFilterType::ParametersType estimatedMeans = kmeansFilter->GetFinalMeans();

  const unsigned int numberOfClasses = estimatedMeans.Size();

  for(unsigned int i = 0; i < numberOfClasses; ++i)
    {
    std::cout << "cluster[" << i << "] ";
    std::cout << "    estimated mean : " << estimatedMeans[i] << std::endl;
    }

  using OutputImageType = KMeansFilterType::OutputImageType;

  using RelabelFilterType = itk::RelabelComponentImageFilter<
                                OutputImageType,
                                OutputImageType >;

  RelabelFilterType::Pointer relabeler = RelabelFilterType::New();

  relabeler->SetInput( kmeansFilter->GetOutput() );

  using RescaleFilterType = itk::RescaleIntensityImageFilter< ImageType, ImageType >;
  RescaleFilterType::Pointer rescaleFilter = RescaleFilterType::New();
  rescaleFilter->SetInput(relabeler->GetOutput());
  rescaleFilter->SetOutputMinimum(0);
  rescaleFilter->SetOutputMaximum(255);

  using SizesType = RelabelFilterType::ObjectSizeInPixelsContainerType;

  const SizesType &  sizes = relabeler->GetSizeOfObjectsInPixels();

  auto sizeItr = sizes.begin();
  auto sizeEnd = sizes.end();

  std::cout << "Number of pixels per class " << std::endl;
  unsigned int kclass = 0;
  while( sizeItr != sizeEnd )
    {
    std::cout << "Class " << kclass << " = " << *sizeItr << std::endl;
    ++kclass;
    ++sizeItr;
    }

  // Visualize
  using ConnectorType = itk::ImageToVTKImageFilter<ImageType>;
  ConnectorType::Pointer originalConnector = ConnectorType::New();
  originalConnector->SetInput(image);
  vtkSmartPointer<vtkImageActor> originalActor =
    vtkSmartPointer<vtkImageActor>::New();
#if VTK_MAJOR_VERSION <= 5
  originalActor->SetInput(originalConnector->GetOutput());
#else
  originalConnector->Update();
  originalActor->SetInputData(originalConnector->GetOutput());
#endif

  ConnectorType::Pointer outputConnector = ConnectorType::New();
  outputConnector->SetInput(rescaleFilter->GetOutput());

  vtkSmartPointer<vtkImageActor> outputActor =
    vtkSmartPointer<vtkImageActor>::New();
#if VTK_MAJOR_VERSION <= 5
  outputActor->SetInput(outputConnector->GetOutput());
#else
  outputConnector->Update();
  outputActor->SetInputData(outputConnector->GetOutput());
#endif

  // There will be one render window
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->SetSize(600, 300);

  vtkSmartPointer<vtkRenderWindowInteractor> interactor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  interactor->SetRenderWindow(renderWindow);

  // Define viewport ranges
  // (xmin, ymin, xmax, ymax)
  double leftViewport[4] = {0.0, 0.0, 0.5, 1.0};
  double rightViewport[4] = {0.5, 0.0, 1.0, 1.0};

  // Setup both renderers
  vtkSmartPointer<vtkRenderer> leftRenderer =
    vtkSmartPointer<vtkRenderer>::New();
  renderWindow->AddRenderer(leftRenderer);
  leftRenderer->SetViewport(leftViewport);
  leftRenderer->SetBackground(.6, .5, .4);

  vtkSmartPointer<vtkRenderer> rightRenderer =
    vtkSmartPointer<vtkRenderer>::New();
  renderWindow->AddRenderer(rightRenderer);
  rightRenderer->SetViewport(rightViewport);
  rightRenderer->SetBackground(.4, .5, .6);
  

  // Add the sphere to the left and the cube to the right
  leftRenderer->AddActor(originalActor);
  rightRenderer->AddActor(outputActor);

  leftRenderer->ResetCamera();
  rightRenderer->ResetCamera();

  renderWindow->Render();

  vtkSmartPointer<vtkInteractorStyleImage> style =
    vtkSmartPointer<vtkInteractorStyleImage>::New();

  interactor->SetInteractorStyle(style);

  interactor->Start();
  
  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;
  size[0] = 200;
  size[1] = 300;

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

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

  itk::ImageRegionIterator<ImageType> imageIterator(image,region);

  while(!imageIterator.IsAtEnd())
    {
    if(imageIterator.GetIndex()[0] > 100 &&
      imageIterator.GetIndex()[0] < 150 &&
      imageIterator.GetIndex()[1] > 100 &&
      imageIterator.GetIndex()[1] < 150)
      {
      imageIterator.Set(100);
      }
    else if(imageIterator.GetIndex()[0] > 50 &&
      imageIterator.GetIndex()[0] < 70 &&
      imageIterator.GetIndex()[1] > 50 &&
      imageIterator.GetIndex()[1] < 70)
      {
      imageIterator.Set(200);
      }
    else
      {
      imageIterator.Set(10);
      }

    ++imageIterator;
  }
}