Examples/Segmentation/WatershedSegmentation2.cxx

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 *  Copyright NumFOCUS
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 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
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// Software Guide : BeginLatex
//
// The following example illustrates how to preprocess and segment images
// using the \doxygen{WatershedImageFilter} for the particular case of
// grayscale scalar image.
//
// Software Guide : EndLatex
 
#include "itkWatershedImageFilter.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkScalarToRGBPixelFunctor.h"
#include "itkUnaryFunctorImageFilter.h"
#include "itkGradientMagnitudeRecursiveGaussianImageFilter.h"
 
 
int
main(int argc, char * argv[])
{
 
 
  if (argc < 5)
  {
    std::cerr << "Missing Parameters " << std::endl;
    std::cerr << "Usage: " << argv[0];
    std::cerr << " inputImage  outputImage lowerThreshold  outputScaleLevel"
              << std::endl;
    return EXIT_FAILURE;
  }
 
  using InternalPixelType = float;
  using RGBPixelType = itk::RGBPixel<unsigned char>;
 
  constexpr unsigned int Dimension = 3;
 
  using InternalImageType = itk::Image<InternalPixelType, Dimension>;
  using RGBImageType = itk::Image<RGBPixelType, Dimension>;
 
 
  const auto input = itk::ReadImage<InternalImageType>(argv[1]);
 
 
  //
  //  Instantiate the GradientMagnitude image filter
  //
  using GradientMagnitudeFilterType =
    itk::GradientMagnitudeRecursiveGaussianImageFilter<InternalImageType,
                                                       InternalImageType>;
 
  auto gradienMagnitudeFilter = GradientMagnitudeFilterType::New();
 
  gradienMagnitudeFilter->SetInput(input);
  gradienMagnitudeFilter->SetSigma(1.0);
 
 
  //
  //  Instantiate the Watershed filter
  //
 
  using WatershedFilterType = itk::WatershedImageFilter<InternalImageType>;
 
  auto watershedFilter = WatershedFilterType::New();
 
  watershedFilter->SetInput(gradienMagnitudeFilter->GetOutput());
 
  watershedFilter->SetThreshold(std::stod(argv[3]));
  watershedFilter->SetLevel(std::stod(argv[4]));
 
 
  //
  //  Instantiate the filter that will encode the label image
  //  into a color image (random color attribution).
  //
 
  using ColormapFunctorType =
    itk::Functor::ScalarToRGBPixelFunctor<unsigned long>;
 
  using LabeledImageType = WatershedFilterType::OutputImageType;
 
  using ColormapFilterType =
    itk::UnaryFunctorImageFilter<LabeledImageType,
                                 RGBImageType,
                                 ColormapFunctorType>;
 
  auto colorMapFilter = ColormapFilterType::New();
 
  colorMapFilter->SetInput(watershedFilter->GetOutput());
 
  try
  {
    itk::WriteImage(colorMapFilter->GetOutput(), argv[2]);
  }
  catch (const itk::ExceptionObject & excep)
  {
    std::cerr << "Exception caught !" << std::endl;
    std::cerr << excep << std::endl;
    return EXIT_FAILURE;
  }
 
 
  return EXIT_SUCCESS;
}