Python實現兩個矩陣的卷積操作

import numpy as np


f = np.array([[1,2,1],
[1,0,0],
[-1,0,1]])
# f = np.array([[3,4,4],
# [1,0,2],
# [-1,0,3]])
img = np.array([
       [2,3,7,4,6,2,9],
       [6,6,9,8,7,4,3],
       [3,4,8,3,8,9,7],
       [7,8,3,6,6,3,4],
       [4,2,1,8,3,4,6],
       [3,2,4,1,9,8,3],
       [0,1,3,9,2,1,4]])

def cov2(img,f,strde):
    inw,inh = img.shape
    w,h=f.shape
    outw = (inw -w )/strde + 1
    outh = (inh -h )/strde + 1
    arr = np.zeros(shape=(outw, outh))
    for g in range(outh):
       for t in range(outw):
          s = 0
          for i in range(w):
              for j in range(h):
                  s+=img[i+g*strde][j+t*strde]*f[i][j]
                  # s = img[i][j] * f[i][j]
          arr[g][t]=s
    return arr

print cov2(img,f,2)