[Insight-users] An exception about the Mutual information metric

[Fang-Chuan Wu]

Hello,

I want to compute the value of an image metric by using Mattes Mutual 
Information metric.

When I executed my program, it catches the exception as following:

---
Exception catched !

itk::ExceptionObject (0xa05aa88)
Location: "Unknown"
File: 
/cygdrive/d/workspace/Insight/Code/Algorithms/itkMattesMutualInformationImageToImageMetric.txx
Line: 705
Description: itk::ERROR: 
MattesMutualInformationImageToImageMetric(0xa056780): Too many samples 
map outside moving image buffer: 0 / 100000
--


The codes I written as following, as fixed image and moving image are:
        Insight/Examples/Data/BrainT1Slice.png
        Insight/Examples/Data/BrainProtonDensitySlice.png

---
#include "metricPlot.h"


int main( int argc, char * argv[] )
{
  if( argc < 3 )
    {
    std::cerr << "Usage: " << std::endl;
    std::cerr << argv[0] << "  fixedImage  movingImage" << std::endl;
    return 1;
    }


  ReaderType::Pointer fixedReader  = ReaderType::New();
  ReaderType::Pointer movingReader = ReaderType::New();
  MetricType::Pointer metric = MetricType::New();
  TransformType::Pointer transform = TransformType::New();
  InterpolatorType::Pointer interpolator = InterpolatorType::New();
  MetricType::TransformParametersType translation( Dimension );

  fixedReader->SetFileName(  argv[ 1 ] );
  movingReader->SetFileName( argv[ 2 ] );

  try
    {
    fixedReader->Update();
    movingReader->Update();
    }
  catch( itk::ExceptionObject & excep )
    {
    std::cerr << "Exception catched !" << std::endl;
    std::cerr << excep << std::endl;
    }

  metric->SetInterpolator( interpolator );
  metric->SetTransform( transform );

  metric->SetNumberOfHistogramBins( 20 );
  metric->SetNumberOfSpatialSamples( 100000 );
  transform->SetIdentity();

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

  //fixedReader->GetOutput()->Print(std::cout);
  //movingReader->GetOutput()->Print(std::cout);

  metric->SetFixedImage(  fixedImage  );
  metric->SetMovingImage( movingImage );

  metric->SetFixedImageRegion(  fixedImage->GetBufferedRegion()  );

  try {
    metric->Initialize();
  }
  catch( itk::ExceptionObject & excep ) {
    std::cerr << "Exception catched !" << std::endl;
    std::cerr << excep << std::endl;
    return -1;
  }

  for(int dx=-20; dx<20; dx++){
    translation[0]=dx;
    try{
      std::cout<<dx<<" "<<metric->GetValue( translation )<<std::endl;
    }
    catch( itk::ExceptionObject & excep ){
      std::cerr << "Exception catched !" << std::endl;
      std::cerr << excep << std::endl;
      return -1;
    }
  }

  return 0;
}
---

Does anyone knows why I get the exception?


Thanks in advace.

Regards,
Benny