ITK/Examples/ImageProcessing/RelabelComponentImageFilter: Difference between revisions

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==Description==
{{warning|1=The media wiki content on this page is no longer maintained. The examples presented on the https://itk.org/Wiki/*  pages likely require ITK version 4.13 or earlier releasesIn many cases, the examples on this page no longer conform to the best practices for modern ITK versions.}}
Relabel the components (blobs) in an image such that consecutive labels are used. This example creates a black image with one rectangle consisting of pixels with value 100 and a second rectangle consisting of pixels with value 200. There are three resulting components (the background and the two rectangles). The relabel filter labels these three components 0, 1, and 2.  
 
==Displayed Output==
The original image and an intensity scaled version of the relabeled image.
 
==RelabelComponentImageFilter.cxx==
<source lang="cpp">
#include "itkImage.h"
#include "itkTranslationTransform.h"
#include "itkImageFileReader.h"
#include "itkNormalizeImageFilter.h"
#include "itkRelabelComponentImageFilter.h"
 
#include <itkImageToVTKImageFilter.h>
 
#include "vtkImageViewer.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkSmartPointer.h"
#include "vtkImageActor.h"
#include "vtkInteractorStyleImage.h"
#include "vtkRenderer.h"
#include "vtkPolyDataMapper.h"
#include "vtkActor.h"
#include "vtkProperty.h"
#include "vtkSphereSource.h"
 
typedef itk::Image<unsigned char, 2>  ImageType;
 
static void CreateImage(ImageType::Pointer image);
 
int main(int, char *[])
{
  ImageType::Pointer image = ImageType::New();
  CreateImage(image);
 
  typedef itk::ImageToVTKImageFilter<ImageType> ConnectorType;
  ConnectorType::Pointer originalConnector = ConnectorType::New();
  originalConnector->SetInput(image);
  vtkSmartPointer<vtkImageActor> originalActor =
    vtkSmartPointer<vtkImageActor>::New();
  originalActor->SetInput(originalConnector->GetOutput());
 
  itk::RelabelComponentImageFilter<ImageType, ImageType>::Pointer relabelFilter =
    itk::RelabelComponentImageFilter<ImageType, ImageType>::New();
  relabelFilter->SetInput(image);
  relabelFilter->Update();
 
  ConnectorType::Pointer relabeledConnector = ConnectorType::New();
  relabeledConnector->SetInput(relabelFilter->GetOutput());
 
  vtkSmartPointer<vtkImageActor> relabeledActor =
    vtkSmartPointer<vtkImageActor>::New();
  relabeledActor->SetInput(relabeledConnector->GetOutput());
 
  // 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(relabeledActor);
 
  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(0);
      }
 
    ++imageIterator;
  }
}
</source>
 
{{ITKVTKCMakeLists|RelabelComponentImageFilter|}}

Latest revision as of 15:50, 7 June 2019

Warning: The media wiki content on this page is no longer maintained. The examples presented on the https://itk.org/Wiki/* pages likely require ITK version 4.13 or earlier releases. In many cases, the examples on this page no longer conform to the best practices for modern ITK versions.