title: Resizing video resolution in OpenCV python
body: <p>I want to reduce the resolution of video that I am getting from my webcam to half(i.e from 640x480 to 320x240) but I am getting error.</p>
  
  <pre><code>import numpy as np
  import cv2
  
  cap = cv2.VideoCapture(0)
  cap.set(3,320)
  cap.set(4,240)
  
  while(True):
  
      # Capture frame-by-frame
      ret, frame = cap.read()
  
      # Our operations on the frame come here
      #gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
  
      # Display the resulting frame
      cv2.imshow('frame',frame)
      if cv2.waitKey(1) &amp; 0xFF == ord('q'):
          break
  
  # When everything done, release the capture
  cap.release()
  cv2.destroyAllWindows()
  </code></pre>
  
  <p>The error that I am getting is </p>
  
  <blockquote>
    <p>Traceback (most recent call last):   File
    "C:\Users\Nemi\Desktop\bbb.py", line 17, in 
        cv2.imshow('frame',frame) error: ......\opencv-2.4.13.2\modules\highgui\src\window.cpp:269: error:
    (-215) size.width>0 &amp;&amp; size.height>0 in function cv::imshow</p>
  </blockquote>
  
  <p>I am new to this and could not find the solution. Could someone please tell me what am I doing wrong?</p>