N4BiasFieldCorrection/N4BiasFieldCorrection.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
 *
 *         http://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.
 *
 *=========================================================================*/
 
#include <SimpleITK.h>
#include <iostream>
#include <stdlib.h>
 
 
namespace sitk = itk::simple;
 
int
main(int argc, char * argv[])
{
 
  if (argc < 2)
  {
    std::cerr << "Usage: N4BiasFieldCorrection inputImage outputImage";
    std::cerr << " [shrinkFactor] [maskImage] [numberOfIterations]";
    std::cerr << " [numberOfFittingLevels]\n";
    return 1;
  }
 
  sitk::Image inputImage = sitk::ReadImage(argv[1], sitk::sitkFloat32);
  sitk::Image image = inputImage;
 
  sitk::Image maskImage;
  if (argc > 4)
  {
    maskImage = sitk::ReadImage(argv[4], sitk::sitkUInt8);
  }
  else
  {
    maskImage = sitk::OtsuThreshold(image, 0, 1, 200);
  }
 
  unsigned int shrinkFactor = 1;
  if (argc > 3)
  {
    shrinkFactor = atoi(argv[3]);
    std::vector<unsigned int> shrink(inputImage.GetDimension(), shrinkFactor);
    image = sitk::Shrink(inputImage, shrink);
    maskImage = sitk::Shrink(maskImage, shrink);
  }
 
  sitk::N4BiasFieldCorrectionImageFilter corrector;
 
  unsigned int numFittingLevels = 4;
 
  if (argc > 6)
  {
    numFittingLevels = atoi(argv[6]);
  }
 
  if (argc > 5)
  {
    unsigned int              it = atoi(argv[5]);
    std::vector<unsigned int> iterations(numFittingLevels, it);
    corrector.SetMaximumNumberOfIterations(iterations);
  }
 
  sitk::Image corrected_image = corrector.Execute(image, maskImage);
 
  sitk::Image log_bias_field = corrector.GetLogBiasFieldAsImage(inputImage);
 
  sitk::Image corrected_image_full_resolution = sitk::Divide(inputImage, sitk::Exp(log_bias_field));
 
  sitk::WriteImage(corrected_image_full_resolution, argv[2]);
 
  if (shrinkFactor > 1)
  {
    sitk::WriteImage(corrected_image, "CXX-Example-N4BiasFieldCorrection-shrunk.nrrd");
  }
 
  if (getenv("SITK_NOSHOW") == NULL)
    sitk::Show(corrected_image, "N4 Corrected");
 
  return 0;
}