title: Python: how to find all connected pixels if I know an origin pixel's position?
body: <p>I have a binary image: <code>numpy.ndarray(dtype=bool)</code>. It has a few hundreds of connected regions filled with <code>True</code> value.</p>
  
  <p>But I'm interested only in one region. I know the posision of one of its elements and want to find out the bounding box of this region-of-interest (and maybe the positions of other points of this region too).</p>
  
  <p>What is the best way to do it?</p>