title: Detecting Circles without using Hough Circles
body: <p>I have an image of a circle, I want to find the circle but not using hough circles.</p>
  
  <p>I found a way, linked <a href="https://math.stackexchange.com/questions/675203/calculating-centre-of-rotation-given-point-coordinates-at-different-positions/1414344#1414344">here</a>. </p>
  
  <p>But I can't find the transition coordinates from white to black as I don't know the x and y coordinates in the circle.  What other methods are there, or how can I make that approach work?</p>
  
  <p>This is my test image:</p>
  
  <p><a href="https://i.stack.imgur.com/u62F7.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/u62F7.jpg" alt="enter image description here"></a></p>