[Insight-users] How can I implement the conversion between itk image and SimpleITK image in Python?

[Hengkai Guo]

Dear all, 

I'm now using SimpleITK in Python. When combining itk with it, I had a problem.

I know the way to implement the conversion between itk image and SimpleITK
image in C++, which is an example in SimpleITK (Examples/ITKIntegration.cxx).

  //
  // Extract the itk image from the SimpleITK image
  //
  InternalImageType::Pointer itkImage =
    dynamic_cast <InternalImageType*>( image.GetITKBase() );
  ...
  //
  // Return to the simpleITK setting by making a SimpleITK image using the
  // output of the blur filter.
  //
  sitk::Image blurredImage = sitk::Image( blurFilter->GetOutput() );

But in Python, when I used "sitk.Image(itkImage)" in which itkImage is an
itkImage, I got an error "this = _SimpleITK.new_Image(*args)
NotImplementedError: Wrong number or type of arguments for overloaded
function 'new_Image'". And in python it's impossible to convert the type
like "dynamic_cast" in C++.

There's one possible solution for this, which use PyBuffer to convert
itkImage into numpy array and then use SimpleITK to convert array into
SimpleITK image finally. But I fail in building the itkPyBuffer. And I think
this method isn't direct to solve this problem.

I have tried my best to search in the Internet, but found nothing. Can you
help me to convert the C++ code into available python code? Thank you.