title: Calculate the area of an object with OpenCV
body: <p>I need to calculate the area of a blob/an object in a grayscale picture (loading it as Mat, not as IplImage) using <em>OpenCV</em>.
  I thought it would be a good idea to get the coordinates of the edges (number of edges change form object to object) or to get all coordinates of the contour and then use <code>contourArea()</code> to calculate the area of my object.</p>
  
  <p>I deleted all noise and got some nice and satisfying contours by using <code>findContours()</code> (programming in <em>C++</em>).</p>
  
  <pre><code>findContours(InputOutputArray image, OutputArrayOfArrays contours, OutputArray hierarchy,int mode, int method, Point offset=Point());
  </code></pre>
  
  <p>Now I got to understand that param <code>contours</code> already owns the coordinates of all contours of my object. Did I get that right?</p>
  
  <p>If yes, it there a way to access them?</p>
  
  <p>And if no, how do I get the coordinates of the contour anyway? </p>