Gray Scale image with OpenCV Python

import cv2
import numpy as np

image_gray = cv2.imread("cow.jpg", cv2.IMREAD_GRAYSCALE)
cv2.imshow("image3", image_gray)

# or just convert from original image
image = cv2.imread("cow.jpg")
image_gray2 = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
cv2.imshow("image4", image_gray2)

cv2.waitKey(0)
cv2.destroyAllWindows()

References
https://github.com/mhdr/OpenCVSamples/tree/master/007