SphinxExamples/src/Core/Common/ApplyAFilterOnlyToASpecifiedRegionOfAnImage/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.
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#include "itkImage.h"
#include "itkRandomImageSource.h"
#include "itkDerivativeImageFilter.h"
 
int
main()
{
  constexpr unsigned int Dimension = 2;
  using PixelType = float;
 
  using ImageType = itk::Image<PixelType, Dimension>;
 
  auto smallSize = ImageType::SizeType::Filled(10);
 
  ImageType::IndexType index{};
 
  ImageType::RegionType region(index, smallSize);
 
  auto bigSize = ImageType::SizeType::Filled(10000);
 
  using RandomSourceType = itk::RandomImageSource<ImageType>;
  auto randomImageSource = RandomSourceType::New();
  randomImageSource->SetNumberOfWorkUnits(1); // to produce non-random results
  randomImageSource->SetSize(bigSize);
  randomImageSource->GetOutput()->SetRequestedRegion(smallSize);
 
  std::cout << "Created random image." << std::endl;
 
  using DerivativeImageFilterType = itk::DerivativeImageFilter<ImageType, ImageType>;
 
  auto derivativeFilter = DerivativeImageFilterType::New();
  derivativeFilter->SetInput(randomImageSource->GetOutput());
  derivativeFilter->SetDirection(0); // "x" axis
  derivativeFilter->GetOutput()->SetRequestedRegion(smallSize);
  derivativeFilter->Update();
 
  std::cout << "Computed derivative." << std::endl;
 
  return EXIT_SUCCESS;
}