title: Distance between edges
body: <p>I want to get the distance (drawn in red) out of this picture. So it is just a straight line from the outer detected edges. I am new to the whole images processing thing in openCV and I could not find a right solution online, so this is why I ask here. I hope somebody can help me.</p>
  <p><img src="https://i.stack.imgur.com/c8PdI.png" alt="enter image description here" /></p>
  <p><img src="https://i.stack.imgur.com/em8rg.png" alt="enter image description here" /></p>