title: Detecting Missing Objects
body: <p>I want to detect missing objects of an image. Here is the situation</p>
  
  <ol>
  <li>You have an image of a room. There is a ball in the room.</li>
  <li>You have another image of the same room (Light conditions similar). The only difference is, the ball is missing.</li>
  <li>Now I need to opencv to compare these 2 images and find what is missing.</li>
  </ol>
  
  <p>I know the first step of doing this, and that is calculating the histogram of both the images and comparing them . If something is missing from the second image, then the histogram values will differ.</p>
  
  <p>Now, how to detect that "ball" is missing? Using template matching? </p>