Opening.py

import numpy as np
import cv2
from matplotlib import pyplot as plt
img = cv2.imread("imgs/chapter5/sudoku.jpg", 0); 
img = cv2.blur(img, (3, 3));


# Otsu's thresholding
ret2,img = cv2.threshold(img,0,255,cv2.THRESH_BINARY_INV+cv2.THRESH_OTSU)

# cv2.MORPH_OPEN
# cv2.morphologyEx

kernel_size = 3;
kernel = np.ones((kernel_size,kernel_size),np.uint8)
opening = cv2.morphologyEx(img, cv2.MORPH_OPEN, kernel)

f = plt.figure(figsize=(15,15))
f.add_subplot(1, 2, 1).set_title('Original Image');
plt.imshow(img, cmap = "gray")
f.add_subplot(1, 2, 2).set_title('opening Image');
plt.imshow(opening, cmap = "gray");
plt.show()