I have a rather silly question: is it somehow possible to extract the bounding boxes from the stroke width transform that is provided by libPillowfight?
It’s not a silly question at all. You’re right, the SWT implementation in libpillowfight does only output images.
I didn’t implement returning the boxes coordinates because I have no use case for it. However if you feel like submitting a patch to add such functions, I’m fine with it.