title: Get floodfill outputs (connected pixels) copied into a new mat
body: <p>Is there a convenient way to create a new Mat from the outputs of a <code>floodfill</code> operation? I want to get a mat of only the pixels which are detected as connected to the seed pixel and are flood filled technically. </p>
  
  <p>Guess that I executed <code>floodFill</code> method to a certain seed point and only 1/4 of the total pixels were filled as they were connected. I want to copy those pixels only to a new image, which represent only those 1/4 number of pixels and most probably smaller than the original input image. </p>
  
  <p>I did this anyway via a very long,higher time+cpu consuming approach. In brief my approach was giving different colors for different <code>floodfill</code> calls and keep records of pixels of same color in a separate data structure, and etc. </p>
  
  <p>I want to know if there is a direct and easier approach using the Mask created by <code>floodfill</code> or using any other approach.</p>