SphinxExamples/src/Filtering/ImageFilterBase/ApplyKernelToEveryPixel/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 "itkNeighborhoodOperatorImageFilter.h"
#include "itkSobelOperator.h"
#include "itkImageFileWriter.h"
#include "itkRescaleIntensityImageFilter.h"
 
using FloatImageType = itk::Image<float, 2>;
 
void
CreateImage(FloatImageType::Pointer image);
void
CastRescaleAndWrite(FloatImageType::Pointer image, const std::string & filename);
 
int
main()
{
  auto image = FloatImageType::New();
  CreateImage(image);
  CastRescaleAndWrite(image, "input.png");
 
  using SobelOperatorType = itk::SobelOperator<float, 2>;
  SobelOperatorType sobelOperator;
  auto              radius = itk::Size<2>::Filled(1); // a radius of 1x1 creates a 3x3 operator
  sobelOperator.SetDirection(0);                      // Create the operator for the X axis derivative
  sobelOperator.CreateToRadius(radius);
 
  using NeighborhoodOperatorImageFilterType = itk::NeighborhoodOperatorImageFilter<FloatImageType, FloatImageType>;
  auto filter = NeighborhoodOperatorImageFilterType::New();
  filter->SetOperator(sobelOperator);
  filter->SetInput(image);
  filter->Update();
 
  CastRescaleAndWrite(filter->GetOutput(), "output.png");
 
  return EXIT_SUCCESS;
}
 
void
CreateImage(FloatImageType::Pointer image)
{
  FloatImageType::IndexType start{};
 
  auto size = FloatImageType::SizeType::Filled(100);
 
  FloatImageType::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 = 20; c < 80; ++c)
    {
      FloatImageType::IndexType pixelIndex;
      pixelIndex[0] = r;
      pixelIndex[1] = c;
 
      image->SetPixel(pixelIndex, 15);
    }
  }
}
 
void
CastRescaleAndWrite(FloatImageType::Pointer image, const std::string & filename)
{
  using UnsignedCharImageType = itk::Image<unsigned char, 2>;
  using RescaleFilterType = itk::RescaleIntensityImageFilter<FloatImageType, UnsignedCharImageType>;
  auto rescaleFilter = RescaleFilterType::New();
  rescaleFilter->SetInput(image);
  rescaleFilter->SetOutputMinimum(0);
  rescaleFilter->SetOutputMaximum(255);
  rescaleFilter->Update();
 
  itk::WriteImage(rescaleFilter->GetOutput(), filename);
}