Trying to implement using image_transport from Python.
Exotica: https://github.com/ipab-slmc/exotica/blob/master/exotica_python/src/Exotica.cpp
Has generic code to transform ANY C++ ROS message into a Python message C++ -> Python.
pyrosmsg: https://github.com/dimatura/pyrosmsg
Has code to transform Images in both directions C++ <-> Python, but seems hardcoded.
I don't know how to deal with this.
If I find out how, I should make a nice tutorial as it's very useful.