GradientAnisotropicDiffusionImageFilter.cxx

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/*=========================================================================

  Program:   ORFEO Toolbox
  Language:  C++
  Date:      $Date$
  Version:   $Revision$


  Copyright (c) Centre National d'Etudes Spatiales. All rights reserved.
  See OTBCopyright.txt for details.


     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/


//  Software Guide : BeginCommandLineArgs
//    INPUTS: {QB_Suburb.png}
//    OUTPUTS: {GradientAnisotropicDiffusionImageFilterOutput.png}
//    5 0.125 3
//  Software Guide : EndCommandLineArgs
//  Software Guide : BeginLatex
//  The \doxygen{itk}{GradientAnisotropicDiffusionImageFilter}  implements an
//  $N$-dimensional version of the classic Perona-Malik anisotropic diffusion
//  equation for scalar-valued images \cite{Perona1990}.
//
//  The conductance term for this implementation is chosen as a function of the
//  gradient magnitude of the image at each point, reducing the strength of
//  diffusion at edge pixels.
//
//  \begin{equation}
//  C(\mathbf{x}) = e^{-(\frac{\parallel \nabla U(\mathbf{x}) \parallel}{K})^2}
//  \end{equation}
//
//  The numerical implementation of this equation is similar to that described
//  in the Perona-Malik paper \cite{Perona1990}, but uses a more robust technique
//  for gradient magnitude estimation and has been generalized to $N$-dimensions.
//
//  \index{itk::Gradient\-Anisotropic\-Diffusion\-Image\-Filter}
//
//  Software Guide : EndLatex

#include "otbImage.h"
#include "otbImageFileReader.h"
#include "otbImageFileWriter.h"
#include "itkRescaleIntensityImageFilter.h"

//  Software Guide : BeginLatex
//
//  The first step required to use this filter is to include its header file.
//
//  \index{itk::Gradient\-Anisotropic\-Diffusion\-Image\-Filter!header}
//
//  Software Guide : EndLatex

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

int main(int argc, char * argv[])
{
  if (argc < 6)
    {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0] << "  inputImageFile  outputImageFile ";
    std::cerr << "numberOfIterations  timeStep  conductance" << std::endl;
    return EXIT_FAILURE;
    }

  //  Software Guide : BeginLatex
  //
  //  Types should be selected based on the pixel types required for the
  //  input and output images.  The image types are defined using the pixel
  //  type and the dimension.
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  typedef    float InputPixelType;
  typedef    float OutputPixelType;

  typedef otb::Image<InputPixelType,  2> InputImageType;
  typedef otb::Image<OutputPixelType, 2> OutputImageType;
  // Software Guide : EndCodeSnippet

  typedef otb::ImageFileReader<InputImageType> ReaderType;

  //  Software Guide : BeginLatex
  //
  //  The filter type is now instantiated using both the input image and the
  //  output image types. The filter object is created by the \code{New()}
  //  method.
  //
  //  \index{itk::Gradient\-Anisotropic\-Diffusion\-Image\-Filter!instantiation}
  //  \index{itk::Gradient\-Anisotropic\-Diffusion\-Image\-Filter!New()}
  //  \index{itk::Gradient\-Anisotropic\-Diffusion\-Image\-Filter!Pointer}
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  typedef itk::GradientAnisotropicDiffusionImageFilter<
      InputImageType, OutputImageType>  FilterType;
  FilterType::Pointer filter = FilterType::New();
  // Software Guide : EndCodeSnippet

  ReaderType::Pointer reader = ReaderType::New();
  reader->SetFileName(argv[1]);

  //  Software Guide : BeginLatex
  //
  //  The input image can be obtained from the output of another filter. Here,
  //  an image reader is used as source.
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  filter->SetInput(reader->GetOutput());
  // Software Guide : EndCodeSnippet

  const unsigned int numberOfIterations = atoi(argv[3]);

  const double timeStep = atof(argv[4]);

  const double conductance = atof(argv[5]);

  //  Software Guide : BeginLatex
  //
  //  This filter requires three parameters, the number of iterations to be
  //  performed, the time step and the conductance parameter used in the
  //  computation of the level set evolution. These parameters are set using
  //  the methods \code{SetNumberOfIterations()}, \code{SetTimeStep()} and
  //  \code{SetConductanceParameter()} respectively.  The filter can be
  //  executed by invoking Update().
  //
  //  \index{itk::Gradient\-Anisotropic\-Diffusion\-Image\-Filter!Update()}
  //  \index{itk::Gradient\-Anisotropic\-Diffusion\-Image\-Filter!SetTimeStep()}
  //  \index{itk::Gradient\-Anisotropic\-Diffusion\-Image\-Filter!SetConductanceParameter()}
  //  \index{itk::Gradient\-Anisotropic\-Diffusion\-Image\-Filter!SetNumberOfIterations()}
  //  \index{SetTimeStep()!itk::Gradient\-Anisotropic\-Diffusion\-Image\-Filter}
  //  \index{SetNumberOfIterations()!itk::Gradient\-Anisotropic\-Diffusion\-Image\-Filter}
  //
  //  Software Guide : EndLatex

  // Software Guide : BeginCodeSnippet
  filter->SetNumberOfIterations(numberOfIterations);
  filter->SetTimeStep(timeStep);
  filter->SetConductanceParameter(conductance);

  filter->Update();
  // Software Guide : EndCodeSnippet

  //  Software Guide : BeginLatex
  //
  //  A typical value for the time step is $0.125$. The number of
  //  iterations is typically set to $5$; more iterations result in
  //  further smoothing and will increase the computing time linearly.
  //
  //  Software Guide : EndLatex

  //
  //  The output of the filter is rescaled here and then sent to a writer.
  //
  typedef unsigned char                 WritePixelType;
  typedef otb::Image<WritePixelType, 2> WriteImageType;
  typedef itk::RescaleIntensityImageFilter<
      OutputImageType, WriteImageType> RescaleFilterType;

  RescaleFilterType::Pointer rescaler = RescaleFilterType::New();
  rescaler->SetOutputMinimum(0);
  rescaler->SetOutputMaximum(255);

  typedef otb::ImageFileWriter<WriteImageType> WriterType;

  WriterType::Pointer writer = WriterType::New();
  writer->SetFileName(argv[2]);

  rescaler->SetInput(filter->GetOutput());
  writer->SetInput(rescaler->GetOutput());
  writer->Update();

  //  Software Guide : BeginLatex
  //
  // \begin{figure} \center
  // \includegraphics[width=0.44\textwidth]{QB_Suburb.eps}
  // \includegraphics[width=0.44\textwidth]{GradientAnisotropicDiffusionImageFilterOutput.eps}
  // \itkcaption[GradientAnisotropicDiffusionImageFilter output]{Effect of the
  // GradientAnisotropicDiffusionImageFilter.}
  // \label{fig:GradientAnisotropicDiffusionImageFilterInputOutput}
  // \end{figure}
  //
  //  Figure
  //  \ref{fig:GradientAnisotropicDiffusionImageFilterInputOutput}
  //  illustrates the effect of this filter. In this example the
  //  filter was run with a time step of $0.125$, and $5$ iterations.
  //  The figure shows how homogeneous regions are
  // smoothed and
  //  edges are preserved.
  //
  //  \relatedClasses
  //  \begin{itemize}
  //  \item \doxygen{itk}{BilateralImageFilter}
  //  \item \doxygen{itk}{CurvatureAnisotropicDiffusionImageFilter}
  //  \item \doxygen{itk}{CurvatureFlowImageFilter}
  //  \end{itemize}
  //
  //  Software Guide : EndLatex

  return EXIT_SUCCESS;
}