import cv2

img = cv2.imread('../images/chess_board.png')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
dst = cv2.cornerHarris(gray, 2, 23, 0.04)
img[dst > 0.01 * dst.max()] = [0, 0, 255]
cv2.imshow('corners', img)
cv2.waitKey()