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>;
 
  auto filter = FilterType::New();
  // Software Guide : EndCodeSnippet
 
 
  using RescalerType =
    itk::RescaleIntensityImageFilter<OutputImageType, OutputImageType>;
 
  auto 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>;
 
  auto reader = ReaderType::New();
  auto 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 (const 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()}
  //
  auto voronoiWriter = VoronoiWriterType::New();
  voronoiWriter->SetFileName(voronoiMapFileName);
  voronoiWriter->SetInput(filter->GetVoronoiMap());
 
  try
  {
    voronoiWriter->Update();
  }
  catch (const 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>;
  auto offsetWriter = WriterOffsetType::New();
  offsetWriter->SetInput(filter->GetVectorDistanceMap());
  offsetWriter->SetFileName(argv[4]);
 
  try
  {
    offsetWriter->Update();
  }
  catch (const 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;
}