text: /*=========================================================================
   *
   *  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 "itkImage.h"
  #include "itkImageFileReader.h"
  #include "itkImageFileWriter.h"
  #include "itkGaussianBlurImageFunction.h"
  #include "itkImageRegionIterator.h"
  
  int
  main(int argc, char * argv[])
  {
    if (argc < 5)
    {
      std::cerr << "Usage: " << std::endl;
      std::cerr << argv[0]
                << "  inputImageFile  outputImageFile sigma maxKernelWidth"
                << std::endl;
      return EXIT_FAILURE;
    }
  
    using ImageType = itk::Image<float, 2>;
    using ReaderType = itk::ImageFileReader<ImageType>;
    using IteratorType = itk::ImageRegionIterator<ImageType>;
    using ConstIteratorType = itk::ImageRegionConstIterator<ImageType>;
  
    auto reader = ReaderType::New();
    reader->SetFileName(argv[1]);
    reader->Update();
  
    const ImageType * inputImage = reader->GetOutput();
  
    ImageType::RegionType region = inputImage->GetBufferedRegion();
  
    ConstIteratorType it(inputImage, region);
  
    auto output = ImageType::New();
  
    output->SetRegions(region);
    output->SetOrigin(inputImage->GetOrigin());
    output->SetSpacing(inputImage->GetSpacing());
    output->Allocate();
  
    IteratorType out(output, region);
  
    using GFunctionType = itk::GaussianBlurImageFunction<ImageType>;
    auto gaussianFunction = GFunctionType::New();
    gaussianFunction->SetInputImage(inputImage);
  
    GFunctionType::ErrorArrayType setError;
    setError.Fill(0.01);
    gaussianFunction->SetMaximumError(setError);
    gaussianFunction->SetSigma(std::stod(argv[3]));
    gaussianFunction->SetMaximumKernelWidth(std::stoi(argv[4]));
  
    it.GoToBegin();
    out.GoToBegin();
  
    while (!it.IsAtEnd())
    {
      out.Set(gaussianFunction->EvaluateAtIndex(it.GetIndex()));
      ++it;
      ++out;
    }
  
    using WriterType = itk::ImageFileWriter<ImageType>;
    auto writer = WriterType::New();
    writer->SetFileName(argv[2]);
    writer->SetInput(output);
    writer->Update();
  
    return EXIT_SUCCESS;
  }
  