title: How does one compare one image to another to see if they are similar by a certain percentage, on the iPhone?
body: <p>I basically want to take two images taken from the camera on the iPhone or iPad 2 and compare them to each other to see if they are pretty much the same. Obviously due to light etc the image will never be EXACTLY the same so I would like to check for around 90% compatibility. </p>
  
  <p>All the other questions like this that I saw on here were either not for iOS or were for locating objects in images. I just want to see if two images are similar.</p>
  
  <p>Thank you.</p>