WikiExamples/ImageProcessing/RecursiveMultiResolutionPyramidImageFilter.cxx

#include "itkImage.h"
#include "itkImageFileWriter.h"
#include "itkRescaleIntensityImageFilter.h"
#include "itkRecursiveMultiResolutionPyramidImageFilter.h"

using UnsignedCharImageType = itk::Image< unsigned char, 2 >;

static void CreateImage(UnsignedCharImageType::Pointer image);

int main(int, char *[])
{
  UnsignedCharImageType::Pointer image = UnsignedCharImageType::New();
  CreateImage(image);
  
  using FloatImageType = itk::Image<float, 2 >;
  
  unsigned int numberOfLevels = 4;
  
  using RecursiveMultiResolutionPyramidImageFilterType = itk::RecursiveMultiResolutionPyramidImageFilter<
      UnsignedCharImageType, FloatImageType>;
  RecursiveMultiResolutionPyramidImageFilterType::Pointer recursiveMultiResolutionPyramidImageFilter =
      RecursiveMultiResolutionPyramidImageFilterType::New();
  recursiveMultiResolutionPyramidImageFilter->SetInput(image);
  recursiveMultiResolutionPyramidImageFilter->SetNumberOfLevels(numberOfLevels);
  recursiveMultiResolutionPyramidImageFilter->Update();

  // This outputs the levels (0 is the lowest resolution)
  for(unsigned int i = 0; i < numberOfLevels; ++i)
    {
    // Scale so we can write to a PNG
    using RescaleFilterType = itk::RescaleIntensityImageFilter< FloatImageType, UnsignedCharImageType >;
    RescaleFilterType::Pointer rescaleFilter = RescaleFilterType::New();
    rescaleFilter->SetInput(recursiveMultiResolutionPyramidImageFilter->GetOutput(i));
    rescaleFilter->SetOutputMinimum(0);
    rescaleFilter->SetOutputMaximum(255);
    rescaleFilter->Update();

    using FileWriterType = itk::ImageFileWriter<UnsignedCharImageType>;
    FileWriterType::Pointer writer = FileWriterType::New();
    std::stringstream ss;
    ss << "output_" << i << ".png";
    std::cout << "Writing " << ss.str() << std::endl;
    writer->SetFileName(ss.str());
    writer->SetInput(rescaleFilter->GetOutput());
    writer->Update();
    }
    
  return EXIT_SUCCESS;
}


void CreateImage(UnsignedCharImageType::Pointer image)
{
  // Create a black image with 2 white regions
  
  UnsignedCharImageType::IndexType start;
  start.Fill(0);

  UnsignedCharImageType::SizeType size;
  size.Fill(200);

  UnsignedCharImageType::RegionType region(start,size);
  image->SetRegions(region);
  image->Allocate();
  image->FillBuffer(0);
  
  // Make a square
  for(unsigned int r = 20; r < 80; r++)
    {
    for(unsigned int c = 30; c < 100; c++)
      {
      UnsignedCharImageType::IndexType pixelIndex;
      pixelIndex[0] = r;
      pixelIndex[1] = c;

      image->SetPixel(pixelIndex, 255);

      }
    }

}