Examples/Filtering/ScaleSpaceGenerator2D.cxx

/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
 
//  Software Guide : BeginLatex
//
//  We now use the previous example for building the ScaleSpace of a 2D image.
//  Since most of the code is the same, we will focus only on the extra lines
//  needed for generating the Scale Space.
//
//  Software Guide : EndLatex
 
 
#include "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkLaplacianRecursiveGaussianImageFilter.h"
 
#include <cstdio>
#include <iomanip>
 
int
main(int argc, char * argv[])
{
  if (argc < 4)
  {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0]
              << "  inputImageFile  outputImageFileBase numberOfSlices"
              << std::endl;
    return EXIT_FAILURE;
  }
 
 
  using InputPixelType = float;
  using OutputPixelType = float;
  using InputImageType = itk::Image<InputPixelType, 2>;
  using OutputImageType = itk::Image<OutputPixelType, 2>;
 
 
  using ReaderType = itk::ImageFileReader<InputImageType>;
 
  using FilterType =
    itk::LaplacianRecursiveGaussianImageFilter<InputImageType,
                                               OutputImageType>;
 
 
  auto reader = ReaderType::New();
  reader->SetFileName(argv[1]);
 
  auto laplacian = FilterType::New();
 
  laplacian->SetNormalizeAcrossScale(true);
 
  laplacian->SetInput(reader->GetOutput());
 
 
  using WriterType = itk::ImageFileWriter<OutputImageType>;
 
  auto writer = WriterType::New();
 
  writer->SetInput(laplacian->GetOutput());
 
 
  //  Software Guide : BeginLatex
  //
  //  Interestingly, all comes down to looping over several scales,
  //  by setting different sigma values and selecting the filename
  //  of the slice corresponding to that scale value.
  //
  //  Software Guide : EndLatex
 
 
  // Software Guide : BeginCodeSnippet
  const int numberOfSlices = std::stoi(argv[3]);
  for (int slice = 0; slice < numberOfSlices; ++slice)
  {
    std::ostringstream filename;
    filename << argv[2] << std::setfill('0') << std::setw(3) << slice
             << ".mhd";
    writer->SetFileName(filename.str());
 
    const float sigma = static_cast<float>(slice) / 10.0 + 1.0;
 
    laplacian->SetSigma(sigma);
    writer->Update();
  }
  // Software Guide : EndCodeSnippet
 
 
  //  Software Guide : BeginLatex
  //
  //  The set of images can now be loaded in a Viewer, such as VolView or
  //  ParaView, and iso-surfaces can be traced at the zero value. These
  //  surfaces will correspond to the zero-crossings of the laplacian and
  //  therefore their stability along Scales will represent the significance
  //  of these features as edges in the original image.
  //
  //  Software Guide : EndLatex
 
 
  return EXIT_SUCCESS;
}