title: What are the possible fast ways to detect circle in an image?
body: <p>What are the possible fast ways to detect circle in an image ?</p>
  
  <p>For ex:
  i have an image with one Big Circle and has 6 small circles inside  big Circle.</p>
  
  <p>I need to find a big circle without using Hough Circles(OpencV).</p>