title: Error level analysis in Image
body: <p>How do I compute ELA for an image? I would like to get similar ELA image using opencv <a href="http://fotoforensics.com/tutorial-ela.php" rel="noreferrer">http://fotoforensics.com/tutorial-ela.php</a></p>
  
  <p>As per this tutorial, I resaved the image at 95% quality jpeg image and using absDiff method to compute the difference between the source image and the resaved image but all I am getting is zero difference.</p>
  
  <p>Any help on how to compute the difference between two images so as to obtain the error level just like sample images in the tutorial?</p>