Examples/Filtering/BinomialBlurImageFilter.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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 *         https://www.apache.org/licenses/LICENSE-2.0.txt
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//  Software Guide : BeginCommandLineArgs
//    INPUTS:  {BrainProtonDensitySlice.png}
//    OUTPUTS: {BinomialBlurImageFilterOutput.png}
//    ARGUMENTS:    5
//  Software Guide : EndCommandLineArgs
 
//  Software Guide : BeginLatex
//
//  The \doxygen{BinomialBlurImageFilter} computes a nearest neighbor average
//  along each dimension. The process is repeated a number of times, as
//  specified by the user. In principle, after a large number of iterations
//  the result will approach the convolution with a Gaussian.
//
//  \index{itk::Binomial\-Blur\-Image\-Filter}
//
//  Software Guide : EndLatex
 
 
#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkRescaleIntensityImageFilter.h"
 
//  Software Guide : BeginLatex
//
//  The first step required to use this filter is to include its header file.
//
//  \index{itk::BinomialBlurImageFilter!header}
//
//  Software Guide : EndLatex
 
// Software Guide : BeginCodeSnippet
#include "itkBinomialBlurImageFilter.h"
// Software Guide : EndCodeSnippet
 
 
int
main(int argc, char * argv[])
{
  if (argc < 4)
  {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0]
              << "  inputImageFile  outputImageFile  numberOfRepetitions"
              << std::endl;
    return EXIT_FAILURE;
  }
 
 
  //  Software Guide : BeginLatex
  //
  //  Types should be chosen for the pixels of the input and output images.
  //  Image types can be instantiated using the pixel type and dimension.
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using InputPixelType = float;
  using OutputPixelType = float;
 
  using InputImageType = itk::Image<InputPixelType, 2>;
  using OutputImageType = itk::Image<OutputPixelType, 2>;
  // Software Guide : EndCodeSnippet
 
 
  using ReaderType = itk::ImageFileReader<InputImageType>;
 
 
  //  Software Guide : BeginLatex
  //
  //  The filter type is now instantiated using both the input image and the
  //  output image types. Then a filter object is created.
  //
  //  \index{itk::BinomialBlurImageFilter!instantiation}
  //  \index{itk::BinomialBlurImageFilter!New()}
  //  \index{itk::BinomialBlurImageFilter!Pointer}
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  using FilterType =
    itk::BinomialBlurImageFilter<InputImageType, OutputImageType>;
  auto filter = FilterType::New();
  // Software Guide : EndCodeSnippet
 
 
  auto reader = ReaderType::New();
  reader->SetFileName(argv[1]);
  const unsigned int repetitions = std::stoi(argv[3]);
 
 
  //  Software Guide : BeginLatex
  //
  //  The input image can be obtained from the output of another filter. Here,
  //  an image reader is used as the source. The number of repetitions is set
  //  with the \code{SetRepetitions()} method. Computation time will increase
  //  linearly with the number of repetitions selected. Finally, the filter
  //  can be executed by calling the \code{Update()} method.
  //
  //  \index{itk::BinomialBlurImageFilter!Update()}
  //  \index{itk::BinomialBlurImageFilter!SetInput()}
  //  \index{itk::BinomialBlurImageFilter!SetRepetitions()}
  //
  //  Software Guide : EndLatex
 
  // Software Guide : BeginCodeSnippet
  filter->SetInput(reader->GetOutput());
  filter->SetRepetitions(repetitions);
  filter->Update();
  // Software Guide : EndCodeSnippet
 
 
  // This section connects the filter output to a writer
  //
  using WritePixelType = unsigned char;
  using WriteImageType = itk::Image<WritePixelType, 2>;
  using RescaleFilterType =
    itk::RescaleIntensityImageFilter<OutputImageType, WriteImageType>;
 
  auto rescaler = RescaleFilterType::New();
  rescaler->SetOutputMinimum(0);
  rescaler->SetOutputMaximum(255);
 
  using WriterType = itk::ImageFileWriter<WriteImageType>;
  auto 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]{BrainProtonDensitySlice}
  // \includegraphics[width=0.44\textwidth]{BinomialBlurImageFilterOutput}
  // \itkcaption[BinomialBlurImageFilter output.]{Effect of the
  // BinomialBlurImageFilter on a slice from a MRI proton density image of the
  // brain.}
  // \label{fig:BinomialBlurImageFilterInputOutput}
  // \end{figure}
  //
  //  Figure \ref{fig:BinomialBlurImageFilterInputOutput} illustrates the
  //  effect of this filter on a MRI proton density image of the brain.
  //
  //  Note that the standard deviation $\sigma$ of the equivalent Gaussian is
  //  fixed.  In the spatial spectrum, the effect of every iteration of this
  //  filter is like a multiplication with a sinus cardinal function.
  //
  //  Software Guide : EndLatex
 
 
  return EXIT_SUCCESS;
}