title: How to detect hologram overlays like the ones in ID Cards?
body: <p>Is there any good way to detect the holograms inside security documents like identity cards? I've tried quite a few methods such as sobel filter, laplacian, among others but its still pretty hard to tell if the card has a hologram over it.</p>
  
  <p>Original Image
  <a href="https://i.stack.imgur.com/87rWL.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/87rWL.jpg" alt="enter image description here"></a></p>
  
  <p>From left to right: Laplacian, SobelX, SobelY
  <a href="https://i.stack.imgur.com/oKqBY.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oKqBY.png" alt="enter image description here"></a></p>