static void ReadPixel(const PixelType&, Image::Pointer image, const itk::Index<3>& index, ScalarType* returnValue)
{
  switch (image->GetDimension())
  {
  case 2:
    {
      ImagePixelReadAccessor<T, 2> readAccess(image, image->GetSliceData(0));
      *returnValue = readAccess.GetPixelByIndex(reinterpret_cast<const itk::Index<2>&>(index));
      break;
    }

  case 3:
    {
      ImagePixelReadAccessor<T, 3> readAccess(image, image->GetVolumeData(0));
      *returnValue = readAccess.GetPixelByIndex(index);
      break;
    }

  default:
    *returnValue = 0;
    break;
  }
}
void mitk::CorrectorAlgorithm::GenerateData()
{
  Image::Pointer inputImage = const_cast<Image*>(ImageToImageFilter::GetInput(0));

  if (inputImage.IsNull() || inputImage->GetDimension() != 2)
  {
    itkExceptionMacro("CorrectorAlgorithm needs a 2D image as input.");
  }

  if (m_Contour.IsNull())
  {
    itkExceptionMacro("CorrectorAlgorithm needs a Contour object as input.");
  }

   // copy the input (since m_WorkingImage will be changed later)
  m_WorkingImage = Image::New();
  m_WorkingImage->Initialize( inputImage );
  m_WorkingImage->SetVolume( inputImage.GetPointer()->GetData() );

  if (inputImage->GetTimeSlicedGeometry() )
  {
    AffineGeometryFrame3D::Pointer originalGeometryAGF = inputImage->GetTimeSlicedGeometry()->Clone();
    TimeSlicedGeometry::Pointer originalGeometry = dynamic_cast<TimeSlicedGeometry*>( originalGeometryAGF.GetPointer() );
    m_WorkingImage->SetGeometry( originalGeometry );
  }
  else
  {
    itkExceptionMacro("Original image does not have a 'Time sliced geometry'! Cannot copy.");
  }

 
  // Convert to ipMITKSegmentationTYPE (because TobiasHeimannCorrectionAlgorithm relys on that data type)
  itk::Image< ipMITKSegmentationTYPE, 2 >::Pointer correctPixelTypeImage;
  CastToItkImage( m_WorkingImage, correctPixelTypeImage );
  assert (correctPixelTypeImage.IsNotNull() );

  // possible bug in CastToItkImage ?
  // direction maxtrix is wrong/broken/not working after CastToItkImage, leading to a failed assertion in
  // mitk/Core/DataStructures/mitkSlicedGeometry3D.cpp, 479:
  // virtual void mitk::SlicedGeometry3D::SetSpacing(const mitk::Vector3D&): Assertion `aSpacing[0]>0 && aSpacing[1]>0 && aSpacing[2]>0' failed
  // solution here: we overwrite it with an unity matrix
  itk::Image< ipMITKSegmentationTYPE, 2 >::DirectionType imageDirection;
  imageDirection.SetIdentity();
  correctPixelTypeImage->SetDirection(imageDirection);

  Image::Pointer temporarySlice = this->GetOutput();
  //  temporarySlice = ImportItkImage( correctPixelTypeImage );
  CastToMitkImage( correctPixelTypeImage, temporarySlice );

  TobiasHeimannCorrectionAlgorithm( temporarySlice->GetSliceData()->GetPicDescriptor() );

  // temporarySlice is our return value (user  can get it by calling GetOutput() )

  CalculateDifferenceImage( temporarySlice, inputImage );
  if ( m_DifferenceImage.IsNotNull() && inputImage->GetTimeSlicedGeometry() )
  {
    AffineGeometryFrame3D::Pointer originalGeometryAGF = inputImage->GetTimeSlicedGeometry()->Clone();
    TimeSlicedGeometry::Pointer originalGeometry = dynamic_cast<TimeSlicedGeometry*>( originalGeometryAGF.GetPointer() );
    m_DifferenceImage->SetGeometry( originalGeometry );
  }
  else
  {
    itkExceptionMacro("Original image does not have a 'Time sliced geometry'! Cannot copy.");
  }
}