import cv2
import numpy as np
from matplotlib import pyplot as plt
img = cv2.imread('chess.png')
rows,cols = img.shape[0:2]
pts1 = np.float32([[20,20],[20,280],[380,20],[380,280]])
pts2 = np.float32([[100,20],[20,280],[300,20],[380,280]])
cv2. circle(img,(20,20),20,(255,0,0),-1)
cv2. circle(img,(20,280),20,(0,255,0),-1)
cv2. circle(img,(380,20),20,(0,0,255),-1)
cv2. circle(img,(380,280),20,(0,255,255),-1)
M = cv2.getPerspectiveTransform(pts1,pts2)
dst = cv2.warpPerspective(img,M,(400,300))
plt.subplot(121),plt.imshow(img),plt.title('image')
plt.subplot(122),plt.imshow(dst),plt.title('perspective')
plt.show()
