python如何实现均值滤波？

import cv2

import numpy as np

def blur_demo(image):           

    """

    均值模糊 : 去随机噪声有很好的去噪效果

    （1, 15）是垂直方向模糊，（15， 1）是水平方向模糊

    """

    dst = cv2.blur(image, (1, 15))   

    cv2.imshow("avg_blur_demo", dst)

def median_blur_demo(image):    # 中值模糊  对椒盐噪声有很好的去燥效果

    dst = cv2.medianBlur(image, 5)

    cv2.imshow("median_blur_demo", dst)

def custom_blur_demo(image):

    """

    用户自定义模糊

    下面除以25是防止数值溢出

    """

    kernel = np.ones([5, 5], np.float32)/25  

    dst = cv2.filter2D(image, -1, kernel)

    cv2.imshow("custom_blur_demo", dst)

src = cv2.imread("./fapiao.png")

img = cv2.resize(src,None,fx=0.8,fy=0.8,interpolation=cv2.INTER_CUBIC)

cv2.imshow('input_image', img)

blur_demo(img)

median_blur_demo(img)

custom_blur_demo(img)

cv2.waitKey(0)

cv2.destroyAllWindows()