图像骨架提取

def extract_skeleton(bw):
    im = np.array(255*bw)
    dst = im.copy()

    num_erode = 0
    while(True):
        if np.sum(dst)==0:
            break
        kernel = cv2.getStructuringElement(cv2.MORPH_CROSS,(3,3))
        dst = cv2.erode(dst,kernel)
        num_erode = num_erode + 1

    skeleton = np.zeros(dst.shape,np.uint8)

    for x in range(num_erode):
        kernel = cv2.getStructuringElement(cv2.MORPH_CROSS,(3,3))
        dst = cv2.erode(im,kernel,None,None,x)
        open_dst = cv2.morphologyEx(dst,cv2.MORPH_OPEN,kernel)
        result = dst - open_dst
        skeleton = skeleton + result

    kernel = cv2.getStructuringElement(cv2.MORPH_CROSS,(3,3))
    skeleton = cv2.dilate(skeleton, kernel)
    
    return skeleton