import cv2 as cv
import numpy as np
import math
import copy

def spilt( a ):
 if a/2 == 0:
  x1 = x2 = a/2
 else:
  x1 = math.floor( a/2 )
  x2 = a - x1
 return -x1,x2

def original (i, j, k,a, b,img):
 x1, x2 = spilt(a)
 y1, y2 = spilt(b)
 temp = np.zeros(a * b)
 count = 0
 for m in range(x1, x2):
  for n in range(y1, y2):
   if i + m < 0 or i + m > img.shape[0] - 1 or j + n < 0 or j + n > img.shape[1] - 1:
    temp[count] = img[i, j, k]
   else:
    temp[count] = img[i + m, j + n, k]
   count += 1
 return temp

def average_function(a , b ,img):
 img0 = copy.copy(img)
 for i in range (0 , img.shape[0] ):
  for j in range (2 ,img.shape[1] ):
   for k in range (img.shape[2]):
    temp = original(i, j, k, a, b, img0)
    img[i,j,k] = int ( np.mean(temp))
 return img 
 
def main():
 img0 = cv.imread(r"noise.jpg")

 ave_img = average_function( 3 , 3, copy.copy(img0) ) #（3，3）滤波器大小 

 cv.imshow("ave_img",ave_img) 
 cv.imshow("original",img0)

 cv.waitKey(0)
 cv.destroyAllWindows()

if __name__ == "__main__":
 main()