SphinxExamples/src/Filtering/ImageGrid/ResampleAnImage/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 "itkLinearInterpolateImageFunction.h"
#include "itkResampleImageFilter.h"
#include "itkScaleTransform.h"
 
int
main(int argc, char * argv[])
{
  if (argc != 4)
  {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0];
    std::cerr << " <InputFileName> <OutputFileName> <scale>";
    std::cerr << std::endl;
    return EXIT_FAILURE;
  }
 
  const char * inputFileName = argv[1];
  const char * outputFileName = argv[2];
  const float  scale = std::stod(argv[3]);
 
  constexpr unsigned int Dimension = 2;
 
  using PixelType = unsigned char;
  using ImageType = itk::Image<PixelType, Dimension>;
  using ScalarType = double;
 
  using ReaderType = itk::ImageFileReader<ImageType>;
  ReaderType::Pointer reader = ReaderType::New();
  reader->SetFileName(inputFileName);
  reader->Update();
 
  ImageType::Pointer inputImage = reader->GetOutput();
 
  ImageType::RegionType  region = inputImage->GetLargestPossibleRegion();
  ImageType::SizeType    size = region.GetSize();
  ImageType::SpacingType spacing = inputImage->GetSpacing();
 
  itk::Index<Dimension> centralPixel;
  centralPixel[0] = size[0] / 2;
  centralPixel[1] = size[1] / 2;
  itk::Point<ScalarType, Dimension> centralPoint;
  centralPoint[0] = centralPixel[0];
  centralPoint[1] = centralPixel[1];
 
  using ScaleTransformType = itk::ScaleTransform<ScalarType, Dimension>;
  ScaleTransformType::Pointer scaleTransform = ScaleTransformType::New();
 
  ScaleTransformType::ParametersType parameters = scaleTransform->GetParameters();
  parameters[0] = scale;
  parameters[1] = scale;
 
  scaleTransform->SetParameters(parameters);
  scaleTransform->SetCenter(centralPoint);
 
  using LinearInterpolatorType = itk::LinearInterpolateImageFunction<ImageType, ScalarType>;
  LinearInterpolatorType::Pointer interpolator = LinearInterpolatorType::New();
 
  using ResampleFilterType = itk::ResampleImageFilter<ImageType, ImageType>;
  ResampleFilterType::Pointer resampleFilter = ResampleFilterType::New();
 
  resampleFilter->SetInput(inputImage);
  resampleFilter->SetTransform(scaleTransform);
  resampleFilter->SetInterpolator(interpolator);
  resampleFilter->SetSize(size);
  resampleFilter->SetOutputSpacing(spacing);
 
  using WriterType = itk::ImageFileWriter<ImageType>;
  WriterType::Pointer writer = WriterType::New();
  writer->SetFileName(outputFileName);
  writer->SetInput(resampleFilter->GetOutput());
 
  try
  {
    writer->Update();
  }
  catch (itk::ExceptionObject & error)
  {
    std::cerr << "Error: " << error << std::endl;
    return EXIT_FAILURE;
  }
 
  return EXIT_SUCCESS;
}