new_contents: #! /usr/bin/env python
  # -*- coding:utf-8 -*-
  
  #
  # Show the images from a USB camera
  #
  
  # External dependencies
  import pickle
  import cv2
  
  # Load calibration file
  with open( 'calibration.pkl', 'rb' ) as calibration_file :
      calibration = pickle.load( calibration_file )
  # Get the camera
  camera = cv2.VideoCapture( 0 )
  # Acquisition loop
  while( True ) :
      # Capture image-by-image
      _, image = camera.read()
      # Undistort the image
      image = cv2.remap( image, calibration['undistort_map'][0], calibration['undistort_map'][1], cv2.INTER_LINEAR )
      # Print ROI
      cv2.rectangle( image, calibration['roi'][:2], calibration['roi'][2:], (0,0,255), 2 )
      # Display the resulting image
      cv2.imshow( 'USB Camera', image )
      # Keyboard interruption
      key = cv2.waitKey( 1 ) & 0xFF
      # Escape : quit the application
      if key == 27 : break
  # Release the camera
  camera.release()
  # Close OpenCV windows
  cv2.destroyAllWindows()
  
subject: Add a script to show undistorted images from the USB camera.