Examples/Filtering/LaplacianImageFilter.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 "itkLaplacianImageFilter.h"
#include "itkZeroCrossingBasedEdgeDetectionImageFilter.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkCastImageFilter.h"
#include "itkRescaleIntensityImageFilter.h"
 
int
main(int argc, char * argv[])
{
  if (argc < 3)
  {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0] << " inputImage outputImage " << std::endl;
    return EXIT_FAILURE;
  }
 
  const char * inputFilename = argv[1];
  const char * outputFilename = argv[2];
 
  using CharPixelType = unsigned char; // IO
  using RealPixelType = double;        // Operations
 
  constexpr unsigned int Dimension = 2;
 
  using CharImageType = itk::Image<CharPixelType, Dimension>;
  using RealImageType = itk::Image<RealPixelType, Dimension>;
 
  using ReaderType = itk::ImageFileReader<CharImageType>;
  using WriterType = itk::ImageFileWriter<CharImageType>;
 
  using CastToRealFilterType =
    itk::CastImageFilter<CharImageType, RealImageType>;
  using CastToCharFilterType =
    itk::CastImageFilter<RealImageType, CharImageType>;
 
  using RescaleFilter =
    itk::RescaleIntensityImageFilter<RealImageType, RealImageType>;
 
  using LaplacianFilter =
    itk::LaplacianImageFilter<RealImageType, RealImageType>;
 
  using ZeroCrossingFilter =
    itk::ZeroCrossingImageFilter<RealImageType, RealImageType>;
 
  // Setting the IO
  auto reader = ReaderType::New();
  auto writer = WriterType::New();
 
  auto toReal = CastToRealFilterType::New();
  auto toChar = CastToCharFilterType::New();
  auto rescale = RescaleFilter::New();
 
  // Setting the ITK pipeline filter
 
  auto lapFilter = LaplacianFilter::New();
  auto zeroFilter = ZeroCrossingFilter::New();
 
  reader->SetFileName(inputFilename);
  writer->SetFileName(outputFilename);
 
  // The output of an edge filter is 0 or 1
  rescale->SetOutputMinimum(0);
  rescale->SetOutputMaximum(255);
 
  toReal->SetInput(reader->GetOutput());
  toChar->SetInput(rescale->GetOutput());
  writer->SetInput(toChar->GetOutput());
 
  // Edge Detection by Laplacian Image Filter:
 
  lapFilter->SetInput(toReal->GetOutput());
  zeroFilter->SetInput(lapFilter->GetOutput());
  rescale->SetInput(zeroFilter->GetOutput());
 
 
  try
  {
    writer->Update();
  }
  catch (const itk::ExceptionObject & err)
  {
    std::cout << "ExceptionObject caught !" << std::endl;
    std::cout << err << std::endl;
    return EXIT_FAILURE;
  }
 
  return EXIT_SUCCESS;
}