WikiExamples/Metrics/MeanSquaresImageToImageMetric.cxx

#include "itkImage.h"
#include "itkImageFileReader.h"
#include "itkMeanSquaresImageToImageMetric.h"
#include "itkLinearInterpolateImageFunction.h"
#include "itkTranslationTransform.h"

int main(int argc, char *argv[])
{
 using ImageType = itk::Image< double, 2 >;
 using ReaderType = itk::ImageFileReader<ImageType>;

 if (argc < 3)
   {
   std::cout << "Usage: " << argv[0] << " imageFile1 imageFile2" << std::endl;
   return EXIT_FAILURE;
   }
 ReaderType::Pointer fixedReader = ReaderType::New();
 fixedReader->SetFileName(argv[1]);
 fixedReader->Update();

 ReaderType::Pointer movingReader = ReaderType::New();
 movingReader->SetFileName(argv[2]);
 movingReader->Update();

 ImageType::Pointer fixedImage = fixedReader->GetOutput();
 ImageType::Pointer movingImage = movingReader->GetOutput();

 using MetricType = itk::MeanSquaresImageToImageMetric < ImageType , ImageType >;
 using InterpolatorType = itk::LinearInterpolateImageFunction<ImageType, double >;
 using TransformType = itk::TranslationTransform < double , 2 >;

 MetricType::Pointer metric = MetricType::New();
 TransformType::Pointer transform = TransformType::New();

 InterpolatorType::Pointer interpolator = InterpolatorType::New();
 interpolator->SetInputImage( fixedImage );

 metric->SetFixedImage( fixedImage );
 metric->SetMovingImage( movingImage );
 metric->SetFixedImageRegion( fixedImage->GetLargestPossibleRegion() );
 metric->SetTransform( transform );
 metric->SetInterpolator( interpolator );

 TransformType::ParametersType params(transform->GetNumberOfParameters());
 params.Fill(0.0);

 metric->Initialize();
 for (double x = -10.0; x <= 10.0; x+=5.0)
   {
   params(0) = x;
   for (double y = -10.0; y <= 10.0; y+=5.0)
     {
     params(1) = y;
     std::cout << params << ": " << metric->GetValue( params ) << std::endl;
     }
   }

 return EXIT_SUCCESS;
}