OpenCV-Python skeletonize function

skeletonize.py

def skeletonize(img):
    """ OpenCV function to return a skeletonized version of img, a Mat object"""

    #  hat tip to http://felix.abecassis.me/2011/09/opencv-morphological-skeleton/

    img = img.copy() # don't clobber original
    skel = img.copy()

    skel[:,:] = 0
    kernel = cv2.getStructuringElement(cv2.MORPH_CROSS, (3,3))

    while True:
        eroded = cv2.morphologyEx(img, cv2.MORPH_ERODE, kernel)
        temp = cv2.morphologyEx(eroded, cv2.MORPH_DILATE, kernel)
        temp  = cv2.subtract(img, temp)
        skel = cv2.bitwise_or(skel, temp)
        img[:,:] = eroded[:,:]
        if cv2.countNonZero(img) == 0:
            break

    return skel