text: import numpy as np
  import cv2
  
  
  img = cv2.imread("chessboardPrinted.jpg")
  gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
  cv2.imshow("Gray", gray)
  
  # Find the chess board corners
  ret, corners = cv2.findChessboardCorners(gray, (7,7),None)
  
  # If found, add object points, image points (after refining them)
  if ret == True:
      # Draw and display the corners
      img = cv2.drawChessboardCorners(img, (8,8), corners,ret)
      cv2.imshow('img',img)
  
  cv2.waitKey(0)
  cv2.destroyAllWindows()