Function CorrectImageTensorDirection

Examples/antsApplyTransforms.cxx:43–74

{
template <typename TensorImageType, typename ImageType>
void
CorrectImageTensorDirection(TensorImageType * movingTensorImage, ImageType * referenceImage)
{
  using DirectionType = typename TensorImageType::DirectionType;
  using MatrixType = typename DirectionType::InternalMatrixType;

  // Assume tensors start in moving voxel space, we want to put them in fixed voxel space

  MatrixType direction =
    referenceImage->GetDirection().GetTranspose() * movingTensorImage->GetDirection().GetVnlMatrix();

  if (!direction.is_identity(0.00001))
  {
    itk::ImageRegionIterator<TensorImageType> It(movingTensorImage, movingTensorImage->GetBufferedRegion());
    for (It.GoToBegin(); !It.IsAtEnd(); ++It)
    {
      using TensorType = typename TensorImageType::PixelType;
      using TensorMatrixType = typename TensorImageType::DirectionType::InternalMatrixType;

      TensorType       tensor = It.Get();
      TensorMatrixType dt;

      Vector2Matrix<TensorType, TensorMatrixType>(tensor, dt);

      dt = direction * dt * direction.transpose();

      tensor = Matrix2Vector<TensorType, TensorMatrixType>(dt);

      It.Set(tensor);
    }
  }
}

template <typename DisplacementFieldType, typename ImageType>
void