python - convert numpy array to cython pointer

Question

I have a numpy array which came from a cv2.imread and so has dtype = np.uint8 and ndim = 3.

I want to convert it to a Cython unsigned int* for use with an external cpp library.

I am trying cdef unsigned int* buff = <unsigned int*>im.data however I get the error Python objects cannot be cast to pointers of primitive types

What am I doing wrong?

Thanks

Answer 1

thanks for your comments. solved by:

cdef np.ndarray[np.uint32_t, ndim=3, mode = 'c'] np_buff = np.ascontiguousarray(im, dtype = np.uint32)
cdef unsigned int* im_buff = <unsigned int*> np_buff.data