SphinxExamples/src/Registration/Common/MultiresolutionPyramidFromImage/Code.cxx

/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#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()
{
  auto 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>;
    auto rescaleFilter = RescaleFilterType::New();
    rescaleFilter->SetInput(recursiveMultiResolutionPyramidImageFilter->GetOutput(i));
    rescaleFilter->SetOutputMinimum(0);
    rescaleFilter->SetOutputMaximum(255);
    rescaleFilter->Update();
 
    std::stringstream ss;
    ss << "output_" << i << ".png";
    std::cout << "Writing " << ss.str() << std::endl;
    itk::WriteImage(rescaleFilter->GetOutput(), ss.str());
  }
 
  return EXIT_SUCCESS;
}
 
 
void
CreateImage(UnsignedCharImageType::Pointer image)
{
  // Create a black image with a white region
 
  UnsignedCharImageType::IndexType start{};
 
  auto size = UnsignedCharImageType::SizeType::Filled(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);
    }
  }
}