title: Check if axes box is empty
body: <p>I'm trying to compare two images using Matlab. The problem is I'm getting the result even if there is nothing in the <em>Axes box</em>. I don't know how to solve this problem.</p>
  
  <p>This is the error I'm getting<img src="https://i.stack.imgur.com/qSoOk.png" alt="enter image description here"></p>
  
  <p>And this is my Output screen </p>
  
  <p><img src="https://i.stack.imgur.com/pD4AU.png" alt="enter image description here"></p>
  
  <p>Any suggestions? 
  Thanks in advance!</p>