title: How to read pixels from a specific video frame
body: <p>I am trying to change a pixel in a specific video frame using OpenCV in Python.
  My current code is:</p>
  
  <pre><code>import cv2
  cap = cv2.VideoCapture("plane.avi")
  cap.set(1, 2) #2- the second frame of my video
  res, frame = cap.read()
  cv2.imshow("video", frame)
  while True:
      ch = 0xFF &amp; cv2.waitKey(1)
      if ch == 27:
          break
  </code></pre>
  
  <p>I got the frame that I want but I don't know how to get and change it's pixels. 
  Please suggest a method.</p>