import cv2 as cv
import numpy as np

img = cv.imread('sudoku.png',0)


 _,th1 =cv.threshold(img,127,255,cv.THRESH_BINARY)

th2=cv.adaptiveThreshold
(img,255,cv.ADAPTIVE_THRESH_MEAN_C,cv.THRESH_BINARY,11,2)

 cv.imshow("Image",img)
 cv.imshow("th1",th1)
 cv.imshow("th2",th2)

 cv.waitKey(0)
 cv.destroyAllWindows()