title: Check if a physical door is opened or closed with OpenCV
body: <p>With a camera i have to check if a real door is opened or closed. It's a normal wooden door (no windows in it) that you can find in any house.</p>
  
  <p>I want to use OpenCV for image recognition. With that i want to recognize the open and closed states of the door.</p>
  
  <p>But i'm not sure which algorithm or detection method i should use for this. What would be the best option for this?</p>
  
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  <p>Edit:</p>
  
  <p>Here is an example image of the door. An idea i had is to just scan a small part of the image (top corner) and check the "closed state" image with the current image. Small example in screenshot aswell.</p>
  
  <p><img src="https://i.stack.imgur.com/UVTNR.jpg" alt="enter image description here"></p>