title: Checking images for similarity with OpenCV
body: <p>Does OpenCV support the comparison of two images, returning some value (maybe a percentage) that indicates how similar these images are? E.g. 100% would be returned if the same image was passed twice, 0% would be returned if the images were totally different.</p>
  
  <p>I already read a lot of similar topics here on StackOverflow. I also did quite some Googling. Sadly I couldn't come up with a satisfying answer.</p>