Examples/Filtering/SignedDanielssonDistanceMapImageFilter.cxx

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// Software Guide : BeginLatex
//
// This example illustrates the use of the
// \doxygen{SignedDanielssonDistanceMapImageFilter}.  This filter generates a
// distance map by running Danielsson distance map twice, once on the input
// image and once on the flipped image.
//
// \index{itk::Signed\-Danielsson\-Distance\-Map\-Image\-Filter!Instantiation}
// \index{itk::Signed\-Danielsson\-Distance\-Map\-Image\-Filter!Header}
//
// The first step required to use this filter is to include its header file.
//
// Software Guide : EndLatex

// Software Guide : BeginCodeSnippet
#include "itkSignedDanielssonDistanceMapImageFilter.h"
// Software Guide : EndCodeSnippet

#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkRescaleIntensityImageFilter.h"


int main( int argc, char * argv[] )
{
  if( argc < 5 )
    {
    std::cerr << "Usage: " << argv[0];
    std::cerr << " inputImageFile outputDistanceMapImageFile ";
    std::cerr << " outputVoronoiMapImageFilter ";
    std::cerr << " outputVectorMapImageFilter ";
    std::cerr << std::endl;
    return EXIT_FAILURE;
    }

  // Software Guide : BeginLatex
  //
  //  Then we must decide what pixel types to use for the input and output
  //  images. Since the output will contain distances measured in pixels, the
  //  pixel type should be able to represent at least the width of the image,
  //  or said in $N$-dimensional terms, the maximum extension along all the dimensions.
  //  The input and output image types are now defined using their respective
  //  pixel type and dimension.
  //
  // Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  using InputPixelType = unsigned char;
  using OutputPixelType = float;
  using VoronoiPixelType = unsigned short;
  constexpr unsigned int Dimension = 2;

  using InputImageType = itk::Image< InputPixelType,  Dimension >;
  using OutputImageType = itk::Image< OutputPixelType, Dimension >;
  using VoronoiImageType = itk::Image< VoronoiPixelType, Dimension >;
  // Software Guide : EndCodeSnippet


  // Software Guide : BeginLatex
  //
  // The only change with respect to the previous example is to replace the
  // DanielssonDistanceMapImageFilter with the
  // SignedDanielssonDistanceMapImageFilter.
  //
  // SoftwareGuide : EndLatex

  // Software Guide : BeginCodeSnippet
  using FilterType = itk::SignedDanielssonDistanceMapImageFilter<
                                         InputImageType,
                                         OutputImageType,
                                         VoronoiImageType >;

  FilterType::Pointer filter = FilterType::New();
  // Software Guide : EndCodeSnippet


  using RescalerType = itk::RescaleIntensityImageFilter<
                   OutputImageType, OutputImageType >;

  RescalerType::Pointer scaler = RescalerType::New();

  // Software Guide : BeginLatex
  //
  // The distances inside the circle are defined to be negative, while the
  // distances outside the circle are positive. To change the convention,
  // use the \code{InsideIsPositive(bool)} function.
  //
  // Software Guide : EndLatex

  // Reader and Writer types are instantiated.
  //
  using ReaderType = itk::ImageFileReader< InputImageType  >;
  using WriterType = itk::ImageFileWriter< OutputImageType >;
  using VoronoiWriterType = itk::ImageFileWriter< VoronoiImageType >;

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

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


  //  The input to the filter is taken from a reader and its output is passed
  //  to a \doxygen{RescaleIntensityImageFilter} and then to a writer.

  filter->SetInput( reader->GetOutput() );
  scaler->SetInput( filter->GetOutput() );
  writer->SetInput( scaler->GetOutput() );

  scaler->SetOutputMaximum( 65535L );
  scaler->SetOutputMinimum( 0L );

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


  const char * voronoiMapFileName = argv[3];

  //  The Voronoi map is obtained with the \code{GetVoronoiMap()} method. In
  //  the lines below we connect this output to the intensity rescaler and
  //  save the result in a file.
  //
  //  \index{itk::Danielsson\-Distance\-Map\-Image\-Filter!GetVoronoiMap()}
  //
  VoronoiWriterType::Pointer voronoiWriter = VoronoiWriterType::New();
  voronoiWriter->SetFileName( voronoiMapFileName );
  voronoiWriter->SetInput( filter->GetVoronoiMap() );

  try
    {
    voronoiWriter->Update();
    }
  catch( itk::ExceptionObject & exp )
    {
    std::cerr << "Exception caught !" << std::endl;
    std::cerr <<     exp    << std::endl;
    }


  //  The distance filter also produces an image of \doxygen{Offset} pixels
  //  representing the vectorial distance to the closest object in the scene.
  //  The type of this output image is defined by the VectorImageType
  //  trait of the filter type.

  using OffsetImageType = FilterType::VectorImageType;

  //  We can use this type for instantiating an \doxygen{ImageFileWriter} type
  //  and creating an object of this class in the following lines.

  using WriterOffsetType = itk::ImageFileWriter< OffsetImageType >;
  WriterOffsetType::Pointer offsetWriter = WriterOffsetType::New();
  offsetWriter->SetInput(  filter->GetVectorDistanceMap()  );
  offsetWriter->SetFileName( argv[4]  );

  try
    {
    offsetWriter->Update();
    }
  catch( itk::ExceptionObject & exp )
    {
    std::cerr << "Exception caught !" << std::endl;
    std::cerr <<     exp    << std::endl;
    }

  //  Software Guide : BeginLatex
  //
  // \begin{figure}
  // \center
  // \includegraphics[width=0.32\textwidth]{Circle}
  // \includegraphics[width=0.32\textwidth]{SignedDanielssonDistanceMapImageFilterOutput}
  // \itkcaption[SignedDanielssonDistanceMapImageFilter
  // output]{SignedDanielssonDistanceMapImageFilter applied on a binary circle image.
  // The intensity has been rescaled for purposes of display.}
  // \label{fig:SignedDanielssonDistanceMapImageFilterInputOutput}
  // \end{figure}
  //
  //  Figure \ref{fig:SignedDanielssonDistanceMapImageFilterInputOutput} illustrates
  //  the effect of this filter. The
  //  input image and the distance map are shown.
  //
  //  \index{Distance Map!itk::Signed\-Danielsson\-Distance\-Map\-Image\-Filter}
  //
  //  Software Guide : EndLatex

  return EXIT_SUCCESS;
}