DisabledFunctionError: cv2.imshow() is disabled in Colab, because it causes Jupyter sessions to crash; see https://github.com/jupyter/notebook/issues/3935. As a substitution, consider using from google.colab.patches import cv2_imshow
from google.colab.patches import cv2_imshow
cv2_imshow('Face no',original_img)
cv2.waitKey(0)