title: How to retireve the co-ordinates using OpenCV?
body: <p>My requirement is to retrieve all the contours and its co-ordinates from an image.
  Currently I'm using cvFindContours to find all the contours and then iterating through each using "CV_GET_SEQ_ELEM"/"cvGetSeqElem" to retrieve all the co-ordinates.</p>
  
  <p>Now a new requirement has a come up where by the size of the contours needs to be x pixels less than the actual.</p>
  
  <p>E.g. 
  If a circle is found having radius of 100 pixels, then the coordinates returned should be 97 (3 pixels less) pixels. In short any contours (any shape) that will be returned will have x pixels less that the actual. </p>
  
  <p>Is there any API to do so. Like findContours with 3 pixels inner than the actual point.</p>
  
  <p><img src="https://i.stack.imgur.com/zD9qR.jpg" alt="Image"></p>
  
  <p>The first image is the source and the second image with yellow part should be returned as co-ordinates.</p>
  
  <p>Thanks,
  Unni</p>