see inline comments:
Well,perhaps we should talk about this a little more, because there are many aspects:- of course, Cython has a more clean feeling- however, it is still not as efficient as C (for some of the code I published, I tried the Cython version first, then switched to C when I saw that it was too slow)
- some older user of the library, less able with python, might still want to develop C code and bind it if there is an easy way to do it
- it is interesting to have some simple C core code, like a function that takes arrays as double * and (w, h) integers, because it enables easy reuse of the core of the algorithm for some other projects (without having to include the whole library) if someone only wants to extract one or two algorithm (this might be interesting when we develop research code and some private company want to use the algorithm )