import cv2
import numpy as np

img=cv2.imread('corner.jpg')
gray=cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
gray=np.float32(gray)

corners=cv2.goodFeaturesToTrack(gray,400,0.01,10)
corners=np.int0(corners)

for corner in corners:
    x,y=corner.ravel()
    cv2.circle(img,(x,y),3,(255,255,0),-1)

cv2.imshow('corner',img)
cv2.waitKey(0)
cv2.destroyAllWindows()
