title: Image boundary detection using python opencv
body: <p>I am newbie who is trying to learn opencv-python in Ubuntu - 14.04. I want to draw the boundary around the black layer at the center of the image that we tested in our laboratory. After finding the boundary i want to perform some action on the image inside boundary. Here is the image <a href="http://prntscr.com/5qfxha" rel="nofollow">http://prntscr.com/5qfxha</a></p>
  
  <p>But all the documents and materials in opencv are provided only for a specific set of images. There is no specific detail of how to deal with custom images. I read every single question and as I told I am newbie i am very confused so please guide me through this. Thanks in advance.</p>