title: find the polygon enclosing the given coordinates and find the coordinates of polygon (python opencv)
body: <p><a href="https://i.stack.imgur.com/96smn.png" rel="nofollow noreferrer">Example image used in program</a></p>
  <p>I am trying to find the coordinates of a polygon in an image
  (just like <strong>flood fill</strong> algorithm we are given a coordinate and we need to search the surrounding pixels for the boundary, if boundary is found we need to append its coordinate to the list if not we need to keep searching other pixels.)and if all the pixels are traversed the program should stop returning the list of pixels.
  usually  color of boundary is black and image is a gray scale image of maps of building.</p>