import cv2
import numpy as np
import math

src = cv2.imread('tekapo.bmp')
rad = 20*math.pi/180
aff = np.array([[math.cos(rad),math.sin(rad),0], [-math.sin(rad),math.cos(rad),0]], dtype=np.float32)
dst = cv2.warpAffine(src, aff, (0,0))

cv2.imshow('src', src)
cv2.imshow('dst', dst)
cv2.waitKey()
cv2.destroyAllWindows()