WikiExamples/ImageProcessing/LabelOverlayImageFilter.cxx

#include "itkBinaryImageToLabelMapFilter.h"
#include "itkImage.h"
#include "itkImageFileWriter.h"
#include "itkImageRegionIterator.h"
#include "itkLabelMapToLabelImageFilter.h"
#include "itkLabelOverlayImageFilter.h"
#include "itkRGBPixel.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 BinaryImageToLabelMapFilterType = itk::BinaryImageToLabelMapFilter<ImageType>;
  BinaryImageToLabelMapFilterType::Pointer binaryImageToLabelMapFilter = BinaryImageToLabelMapFilterType::New();
  binaryImageToLabelMapFilter->SetInput(image);
  binaryImageToLabelMapFilter->Update();
  
  using LabelMapToLabelImageFilterType = itk::LabelMapToLabelImageFilter<BinaryImageToLabelMapFilterType::OutputImageType, ImageType>;
  LabelMapToLabelImageFilterType::Pointer labelMapToLabelImageFilter = LabelMapToLabelImageFilterType::New();
  labelMapToLabelImageFilter->SetInput(binaryImageToLabelMapFilter->GetOutput());
  labelMapToLabelImageFilter->Update();

  using RGBPixelType = itk::RGBPixel<unsigned char>;
  using RGBImageType = itk::Image<RGBPixelType>;
  
  using LabelOverlayImageFilterType = itk::LabelOverlayImageFilter<ImageType, ImageType, RGBImageType>;
  LabelOverlayImageFilterType::Pointer labelOverlayImageFilter = LabelOverlayImageFilterType::New();
  labelOverlayImageFilter->SetInput(image);
  labelOverlayImageFilter->SetLabelImage(labelMapToLabelImageFilter->GetOutput());
  labelOverlayImageFilter->SetOpacity(.5);
  labelOverlayImageFilter->Update();
  
  using WriterType = itk::ImageFileWriter< RGBImageType  >;
  WriterType::Pointer writer = WriterType::New();
  writer->SetFileName("output.png");
  writer->SetInput(labelOverlayImageFilter->GetOutput());
  writer->Update();
  
  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(100);

  ImageType::RegionType region;
  region.SetSize(size);
  region.SetIndex(start);
  image->SetRegions(region);
  image->Allocate();
  image->FillBuffer(0);

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

  // Make two squares
  while(!imageIterator.IsAtEnd())
    {
    if((imageIterator.GetIndex()[0] > 5 && imageIterator.GetIndex()[0] < 20) &&
      (imageIterator.GetIndex()[1] > 5 && imageIterator.GetIndex()[1] < 20) )
        {
        imageIterator.Set(255);
        }
        
    if((imageIterator.GetIndex()[0] > 50 && imageIterator.GetIndex()[0] < 70) &&
      (imageIterator.GetIndex()[1] > 50 && imageIterator.GetIndex()[1] < 70) )
        {
        imageIterator.Set(255);
        }
    ++imageIterator;
    }
    
  using WriterType = itk::ImageFileWriter< ImageType  >;
  WriterType::Pointer writer = WriterType::New();
  writer->SetFileName("image.png");
  writer->SetInput(image);
  writer->Update();
}