Examples/Segmentation/CannySegmentationLevelSetImageFilter.cxx

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 *  Copyright NumFOCUS
 *
 *  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 : BeginCommandLineArgs
//    INPUTS:  {BrainProtonDensitySlice.png}
//    INPUTS:  {ThresholdSegmentationLevelSetImageFilterVentricle.png}
//    OUTPUTS: {CannySegmentationLevelSetImageFilterVentricle1.png}
//    ARGUMENTS:    7.0 0.1 -10.0 127.5 15
//  Software Guide : EndCommandLineArgs
 
// Software Guide : BeginLatex
//
// \index{itk::Canny\-Segmentation\-LevelSet\-Image\-Filter}
//
// The \doxygen{CannySegmentationLevelSetImageFilter} defines a speed term
// that minimizes distance to the Canny edges in an image.  The initial
// level set model moves through a gradient advection field until it locks
// onto those edges.  This filter is more suitable for refining existing
// segmentations than as a region-growing algorithm.
//
// The two terms defined for the CannySegmentationLevelSetImageFilter
// are the advection term and the propagation term from
// Equation~\ref{eqn:LevelSetEquation}.  The advection term is constructed by
// minimizing the squared distance transform from the Canny edges.
//
// \begin{equation}
// \label{eqn:CannySegmentationLevelSetImageFilterAdvection}
// \mbox{min} \int D^2 \Rightarrow D \nabla D
// \end{equation}
//
// where the distance transform $D$ is calculated using a
// \doxygen{DanielssonDistanceMapImageFilter} applied to the output of the
// \doxygen{CannyEdgeDetectionImageFilter}.
//
// For cases in which some surface expansion is to be allowed, a non-zero
// value may be set for the propagation term.  The propagation term is simply
// $D$.  As with all ITK level set segmentation filters, the curvature term
// controls the smoothness of the surface.
//
// CannySegmentationLevelSetImageFilter expects two inputs.  The first is an
// initial level set in the form of an \doxygen{Image}. The second input is
// the feature image $g$ from which propagation and advection terms are
// calculated.  It is generally a good idea to do some preprocessing of the
// feature image to remove noise.
//
// Figure~\ref{fig:CannySegmentationLevelSetImageFilterDiagram} shows how the
// image processing pipeline is constructed.  We read two images: the image to
// segment and the image that contains the initial implicit surface.  The goal
// is to refine the initial model from the second input and not to grow a new
// segmentation from seed points. The \code{feature} image is preprocessed
// with a few iterations of an anisotropic diffusion filter.
//
// \begin{figure} \center
// \includegraphics[width=0.9\textwidth]{CannySegmentationLevelSetImageFilterCollaborationDiagram1}
// \itkcaption[CannySegmentationLevelSetImageFilter collaboration
// diagram]{Collaboration diagram for the CannySegmentationLevelSetImageFilter
// applied to a segmentation task.}
// \label{fig:CannySegmentationLevelSetImageFilterDiagram}
// \end{figure}
//
// Let's start by including the appropriate header file.
//
// Software Guide : EndLatex
 
 
#include "itkImage.h"
 
// Software Guide : BeginCodeSnippet
#include "itkCannySegmentationLevelSetImageFilter.h"
#include "itkGradientAnisotropicDiffusionImageFilter.h"
// Software Guide : EndCodeSnippet
 
#include "itkFastMarchingImageFilter.h"
#include "itkBinaryThresholdImageFilter.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkZeroCrossingImageFilter.h"
 
int
main(int argc, char * argv[])
{
  if (argc < 9)
  {
    std::cerr << "Missing Parameters " << std::endl;
    std::cerr << "Usage: " << argv[0];
    std::cerr << " InputImage  InitialModel OutputImage";
    std::cerr << " CannyThreshold ";
    std::cerr << " CannyVariance ";
    std::cerr << " AdvectionWeight";
    std::cerr << " InitialModelIsovalue";
    std::cerr << " MaximumIterations";
    std::cerr << " [OutputSpeedImage]" << std::endl;
    return EXIT_FAILURE;
  }
 
  //  Software Guide : BeginLatex
  //
  //  We define the image type using a particular pixel type and
  //  dimension. In this case we will use 2D \code{float} images.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using InternalPixelType = float;
  constexpr unsigned int Dimension = 2;
  using InternalImageType = itk::Image<InternalPixelType, Dimension>;
  // Software Guide : EndCodeSnippet
 
  using OutputPixelType = unsigned char;
  using OutputImageType = itk::Image<OutputPixelType, Dimension>;
  using ThresholdingFilterType =
    itk::BinaryThresholdImageFilter<InternalImageType, OutputImageType>;
 
  auto thresholder = ThresholdingFilterType::New();
 
  thresholder->SetUpperThreshold(10.0);
  thresholder->SetLowerThreshold(0.0);
 
  thresholder->SetOutsideValue(0);
  thresholder->SetInsideValue(255);
 
  using ReaderType = itk::ImageFileReader<InternalImageType>;
  using WriterType = itk::ImageFileWriter<OutputImageType>;
 
  auto reader1 = ReaderType::New();
  auto reader2 = ReaderType::New();
  auto writer = WriterType::New();
 
  reader1->SetFileName(argv[1]);
  reader2->SetFileName(argv[2]);
  writer->SetFileName(argv[3]);
 
  //  Software Guide : BeginLatex
  //
  //  The input image will be processed with a few iterations of
  //  feature-preserving diffusion.  We create a filter and set the
  //  appropriate parameters.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using DiffusionFilterType =
    itk::GradientAnisotropicDiffusionImageFilter<InternalImageType,
                                                 InternalImageType>;
  auto diffusion = DiffusionFilterType::New();
  diffusion->SetNumberOfIterations(5);
  diffusion->SetTimeStep(0.125);
  diffusion->SetConductanceParameter(1.0);
  // Software Guide : EndCodeSnippet
 
  //  Software Guide : BeginLatex
  //
  //  The following lines define and instantiate a
  //  CannySegmentationLevelSetImageFilter.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using CannySegmentationLevelSetImageFilterType =
    itk::CannySegmentationLevelSetImageFilter<InternalImageType,
                                              InternalImageType>;
  auto cannySegmentation = CannySegmentationLevelSetImageFilterType::New();
  // Software Guide : EndCodeSnippet
 
 
  //  Software Guide : BeginLatex
  //
  // As with the other ITK level set segmentation filters, the terms of the
  // CannySegmentationLevelSetImageFilter level set equation can be
  // weighted by scalars.  For this application we will modify the relative
  // weight of the advection term.  The propagation and curvature term weights
  // are set to their defaults of $0$ and $1$, respectively.
  //
  //  \index{itk::Canny\-Segmentation\-LevelSet\-Image\-Filter!SetAdvectionScaling()}
  //  \index{itk::Segmentation\-LevelSet\-ImageFilter!SetAdvectionScaling()}
  //
  //  Software Guide : EndLatex
 
  //  Software Guide : BeginCodeSnippet
  cannySegmentation->SetAdvectionScaling(std::stod(argv[6]));
  cannySegmentation->SetCurvatureScaling(1.0);
  cannySegmentation->SetPropagationScaling(0.0);
  //  Software Guide : EndCodeSnippet
 
 
  //  Software Guide : BeginLatex
  //
  //  The maximum number of iterations is specified from the command line.
  //  It may not be desirable in some applications to run the filter to
  //  convergence.  Only a few iterations may be required.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  cannySegmentation->SetMaximumRMSError(0.01);
  cannySegmentation->SetNumberOfIterations(std::stoi(argv[8]));
  // Software Guide : EndCodeSnippet
 
  //  Software Guide : BeginLatex
  //
  //  There are two important parameters in the
  //  CannySegmentationLevelSetImageFilter to control the behavior of the
  //  Canny edge detection.  The \emph{variance} parameter controls the
  //  amount of Gaussian smoothing on the input image.  The \emph{threshold}
  //  parameter indicates the lowest allowed value in the output image.
  //  Thresholding is used to suppress Canny edges whose gradient magnitudes
  //  fall below a certain value.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  cannySegmentation->SetThreshold(std::stod(argv[4]));
  cannySegmentation->SetVariance(std::stod(argv[5]));
  // Software Guide : EndCodeSnippet
 
 
  // Software Guide : BeginLatex
  //
  // Finally, it is very important to specify the isovalue of the surface in
  // the initial model input image. In a binary image, for example, the
  // isosurface is found midway between the foreground and background values.
  //
  // Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  cannySegmentation->SetIsoSurfaceValue(std::stod(argv[7]));
  // Software Guide : EndCodeSnippet
 
  //  Software Guide : BeginLatex
  //
  //  The filters are now connected in a pipeline indicated in
  //  Figure~\ref{fig:CannySegmentationLevelSetImageFilterDiagram}.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  diffusion->SetInput(reader1->GetOutput());
  cannySegmentation->SetInput(reader2->GetOutput());
  cannySegmentation->SetFeatureImage(diffusion->GetOutput());
  thresholder->SetInput(cannySegmentation->GetOutput());
  writer->SetInput(thresholder->GetOutput());
  // Software Guide : EndCodeSnippet
 
 
  //  Software Guide : BeginLatex
  //
  //  Invoking the \code{Update()} method on the writer triggers the
  //  execution of the pipeline.  As usual, the call is placed in a
  //  \code{try/catch} block to handle any exceptions that may be thrown.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  try
  {
    writer->Update();
  }
  catch (const itk::ExceptionObject & excep)
  {
    std::cerr << "Exception caught !" << std::endl;
    std::cerr << excep << std::endl;
    return EXIT_FAILURE;
  }
  // Software Guide : EndCodeSnippet
 
  // Print out some useful information
  std::cout << std::endl;
  std::cout << "Max. no. iterations: "
            << cannySegmentation->GetNumberOfIterations() << std::endl;
  std::cout << "Max. RMS error: " << cannySegmentation->GetMaximumRMSError()
            << std::endl;
  std::cout << std::endl;
  std::cout << "No. elpased iterations: "
            << cannySegmentation->GetElapsedIterations() << std::endl;
  std::cout << "RMS change: " << cannySegmentation->GetRMSChange()
            << std::endl;
 
  //  Software Guide : BeginLatex
  //
  //  We can use this filter to make some subtle refinements to the ventricle
  //  segmentation from the previous example that used the
  //  \doxygen{ThresholdSegmentationLevelSetImageFilter}.  The application
  //  was run using \code{Examples/Data/BrainProtonDensitySlice.png} and
  //  \code{Examples/Data/VentricleModel.png} as inputs, a \code{threshold}
  //  of $7.0$, \code{variance} of $0.1$, \code{advection weight} of $10.0$,
  //  and an initial isosurface value of $127.5$.  One case was run for $15$
  //  iterations and the second was run to convergence.  Compare the results
  //  in the two rightmost images of
  //  Figure~\ref{fig:CannySegmentationLevelSetImageFilter} with the
  //  ventricle segmentation from
  //  Figure~\ref{fig:ThresholdSegmentationLevelSetImageFilter} shown in the
  //  middle.  Jagged edges are straightened and the small spur at the upper
  //  right-hand side of the mask has been removed.
  //
  //  \begin{figure}
  //  \includegraphics[width=0.24\textwidth]{BrainProtonDensitySlice}
  //  \includegraphics[width=0.24\textwidth]{ThresholdSegmentationLevelSetImageFilterVentricle}
  //  \includegraphics[width=0.24\textwidth]{CannySegmentationLevelSetImageFilterVentricle1}
  //  \includegraphics[width=0.24\textwidth]{CannySegmentationLevelSetImageFilterVentricle2}
  //  \itkcaption[Segmentation results of CannyLevelSetImageFilter]{Results of
  //  applying the CannySegmentationLevelSetImageFilter to a prior ventricle
  //  segmentation.  Shown from left to right are the original image, the
  //  prior segmentation of the ventricle from
  //  Figure~\ref{fig:ThresholdSegmentationLevelSetImageFilter}, $15$
  //  iterations of the CannySegmentationLevelSetImageFilter, and the
  //  CannySegmentationLevelSetImageFilter run to convergence.}
  //  \label{fig:CannySegmentationLevelSetImageFilter}
  //  \end{figure}
  //
  //  The free parameters of this filter can be adjusted to achieve a wide
  //  range of shape variations from the original model.  Finding the right
  //  parameters for your particular application is usually a process of
  //  trial and error.  As with most ITK level set segmentation filters,
  //  examining the propagation (speed) and advection images can help the
  //  process of tuning parameters.  These images are available using
  //  \code{Set/Get} methods from the filter after it has been updated.
  //
  //  Software Guide : EndLatex
 
  if (argc > 9)
  {
    const char * speedImageFileName = argv[9];
 
    //  Software Guide : BeginLatex
    //
    // In some cases it is interesting to take a direct look at the speed
    // image used internally by this filter. This may help for setting the
    // correct parameters for driving the segmentation. In order to obtain
    // such speed image, the method \code{GenerateSpeedImage()} should be
    // invoked first. Then we can recover the speed image with the
    // \code{GetSpeedImage()} method as illustrated in the following lines.
    //
    //  \index{itk::Canny\-Segmentation\-LevelSet\-Image\-Filter!GenerateSpeedImage()}
    //  \index{itk::Segmentation\-LevelSet\-ImageFilter!GenerateSpeedImage()}
    //  \index{itk::Canny\-Segmentation\-LevelSet\-Image\-Filter!GetSpeedImage()}
    //  \index{itk::Segmentation\-LevelSet\-ImageFilter!GetSpeedImage()}
    //
    //  Software Guide : EndLatex
 
    //  Software Guide : BeginCodeSnippet
    cannySegmentation->GenerateSpeedImage();
 
    using SpeedImageType =
      CannySegmentationLevelSetImageFilterType::SpeedImageType;
    using SpeedWriterType = itk::ImageFileWriter<SpeedImageType>;
    auto speedWriter = SpeedWriterType::New();
 
    speedWriter->SetInput(cannySegmentation->GetSpeedImage());
    //  Software Guide : EndCodeSnippet
 
 
    speedWriter->SetFileName(speedImageFileName);
 
    try
    {
      speedWriter->Update();
    }
    catch (const itk::ExceptionObject & excep)
    {
      std::cerr << "Exception caught ! while writing the speed image"
                << std::endl;
      std::cerr << "Filename : " << speedImageFileName << std::endl;
      std::cerr << excep << std::endl;
      return EXIT_FAILURE;
    }
  }
 
  return EXIT_SUCCESS;
}