Examples/Segmentation/WatershedSegmentation2.cxx

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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 >;


  //
  // We instantiate reader and writer types
  //
  using ReaderType = itk::ImageFileReader< InternalImageType   >;
  using WriterType = itk::ImageFileWriter< RGBImageType  >;

  ReaderType::Pointer reader = ReaderType::New();
  WriterType::Pointer writer = WriterType::New();

  reader->SetFileName( argv[1] );
  writer->SetFileName( argv[2] );


  //
  //  Instantiate the GradientMagnitude image filter
  //
  using GradientMagnitudeFilterType =
           itk::GradientMagnitudeRecursiveGaussianImageFilter<
               InternalImageType, InternalImageType >;

  GradientMagnitudeFilterType::Pointer gradienMagnitudeFilter = GradientMagnitudeFilterType::New();

  gradienMagnitudeFilter->SetInput( reader->GetOutput() );
  gradienMagnitudeFilter->SetSigma( 1.0 );


  //
  //  Instantiate the Watershed filter
  //

  using WatershedFilterType = itk::WatershedImageFilter<InternalImageType>;

  WatershedFilterType::Pointer 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 >;

  ColorMapFilterType::Pointer colorMapFilter = ColorMapFilterType::New();

  colorMapFilter->SetInput(  watershedFilter->GetOutput() );

  writer->SetInput( colorMapFilter->GetOutput() );

  try
    {
    writer->Update();
    }
  catch( itk::ExceptionObject & excep )
    {
    std::cerr << "Exception caught !" << std::endl;
    std::cerr << excep << std::endl;
    return EXIT_FAILURE;
    }


  return EXIT_SUCCESS;

}