SphinxExamples/src/Filtering/ImageGrid/UpsampleOrDownsampleScalarImage/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
 *
 *         http://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 "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkResampleImageFilter.h"
#include "itkIdentityTransform.h"
 
int
main(int argc, char * argv[])
{
  if (argc != 5)
  {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0];
    std::cerr << " <InputFileName> <OutputFileName> <size X> <size Y>";
    std::cerr << std::endl;
    return EXIT_FAILURE;
  }
 
  constexpr unsigned int Dimension = 2;
 
  using PixelType = unsigned char;
  using ImageType = itk::Image<PixelType, Dimension>;
 
  const char * inputFileName = argv[1];
  const char * outputFileName = argv[2];
 
  ImageType::SizeType outputSize;
 
  for (unsigned int dim = 0, k = 3; dim < Dimension; dim++)
  {
    outputSize[dim] = std::stoi(argv[k++]);
  }
 
  using ReaderType = itk::ImageFileReader<ImageType>;
  ReaderType::Pointer reader = ReaderType::New();
  reader->SetFileName(inputFileName);
  reader->UpdateOutputInformation();
 
  ImageType::Pointer inputImage = reader->GetOutput();
 
  ImageType::SizeType inputSize = inputImage->GetLargestPossibleRegion().GetSize();
  std::cout << "Input Size: " << inputSize << std::endl;
 
  ImageType::SpacingType inputSpacing = inputImage->GetSpacing();
  std::cout << "Input Spacing: " << inputSpacing << std::endl;
 
  ImageType::SpacingType outputSpacing;
 
  for (unsigned int dim = 0; dim < Dimension; dim++)
  {
    outputSpacing[dim] = static_cast<double>(inputSpacing[dim]) * static_cast<double>(inputSize[dim]) /
                         static_cast<double>(outputSize[dim]);
  }
 
  std::cout << "Output Size: " << outputSize << std::endl;
  std::cout << "Output Spacing: " << outputSpacing << std::endl;
 
  using TransformPrecisionType = double;
  using TransformType = itk::IdentityTransform<TransformPrecisionType, Dimension>;
  using FilterType = itk::ResampleImageFilter<ImageType, ImageType>;
  FilterType::Pointer filter = FilterType::New();
  filter->SetInput(inputImage);
  filter->SetSize(outputSize);
  filter->SetOutputSpacing(outputSpacing);
  filter->SetOutputOrigin(inputImage->GetOrigin());
  filter->SetTransform(TransformType::New());
 
  using WriterType = itk::ImageFileWriter<ImageType>;
  WriterType::Pointer writer = WriterType::New();
  writer->SetFileName(outputFileName);
  writer->SetInput(filter->GetOutput());
  try
  {
    writer->Update();
  }
  catch (itk::ExceptionObject & error)
  {
    std::cerr << "Error: " << error << std::endl;
    return EXIT_FAILURE;
  }
 
  return EXIT_SUCCESS;
}