ITK/Examples/ImageProcessing/ManuallyRemovingLabels: Difference between revisions

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==ManuallyRemovingLabels.cxx==
{{warning|1=The media wiki content on this page is no longer maintained.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.
<source lang="cpp">
}}
#include "itkImage.h"
#include "itkImageFileWriter.h"
#include "itkImageRegionIterator.h"
#include "itkBinaryImageToLabelMapFilter.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::BinaryImageToLabelMapFilter<ImageType> BinaryImageToLabelMapFilterType;
  BinaryImageToLabelMapFilterType::Pointer binaryImageToLabelMapFilter = BinaryImageToLabelMapFilterType::New();
  binaryImageToLabelMapFilter->SetInput(image);
  binaryImageToLabelMapFilter->Update();
  // The output of this filter is an itk::LabelMap, which contains itk::LabelObject's
  std::cout << "There are " << binaryImageToLabelMapFilter->GetOutput()->GetNumberOfLabelObjects() << " objects." << std::endl;
 
  std::vector<unsigned long> labelsToRemove;
 
  std::cout << "There are originally " << binaryImageToLabelMapFilter->GetOutput()->GetNumberOfLabelObjects() << " objects." << std::endl;
 
  // Note: do NOT remove the labels inside the loop! The IDs are stored such that they will change when one is deleted.
  // Instead, mark all of the labels to be removed first and then remove them all together.
  for(unsigned int i = 0; i < binaryImageToLabelMapFilter->GetOutput()->GetNumberOfLabelObjects(); i++)
    {
    // Get the ith region
    BinaryImageToLabelMapFilterType::OutputImageType::LabelObjectType* labelObject = binaryImageToLabelMapFilter->GetOutput()->GetNthLabelObject(i);
    //std::cout << "Region " << i << " has " << labelObject->Size() << " pixels." << std::endl;
 
    // Mark every other label to be removed
    if(i%2 == 0)
      {
      labelsToRemove.push_back(labelObject->GetLabel());
      }
    }
   
  std::cout << "Removing " << labelsToRemove.size() << " objects." << std::endl;
  // Remove all regions that were marked for removal.
  for(unsigned int i = 0; i < labelsToRemove.size(); ++i)
    {
    binaryImageToLabelMapFilter->GetOutput()->RemoveLabel(labelsToRemove[i]);
    }
 
  std::cout << "There are " << binaryImageToLabelMapFilter->GetOutput()->GetNumberOfLabelObjects()
            << " objects remaining." << std::endl;
 
  return EXIT_SUCCESS;
}
   
void CreateImage(ImageType::Pointer image)
{
  // Create a black image with a white square
  ImageType::IndexType start;
  start.Fill(0);
  ImageType::SizeType size;
  size.Fill(20);
   ImageType::RegionType region(start,size);
  image->SetRegions(region);
  image->Allocate();
  image->FillBuffer(0);
 
  // Make line of non-touching diagonal pixels
  for(unsigned int i = 0; i < 20; i+=2)
    {
    itk::Index<2> pixel;
    pixel[0] = i;
    pixel[1] = i;
    image->SetPixel(pixel, 255);
    }
}
 
</source>
 
{{ITKVTKCMakeLists|{{SUBPAGENAME}}}}

Latest revision as of 19:07, 4 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.