text: import numpy as np
  
  import cv2
  
  from matplotlib import pylab as plt
  
  picNumber = 1
  filename =  "/home/cwu/project/stereo-calibration/calib_imgs/3/left/left_" + str(picNumber) +".jpg"
  img = cv2.imread(filename)
  gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
  
  maxCornerNumber = 300
  minDistance = 0.01
  blockSize = 10
  corners = cv2.goodFeaturesToTrack(gray,maxCornerNumber,minDistance, blockSize)
  corners = np.int0(corners)
  
  dotSize = 4
  for i in corners:
      x,y = i.ravel()
      cv2.circle(img,(x,y), dotSize ,255,-1)
  
  plt.imshow(img),plt.show()
  