code: def computeRange(corners):
      
      x = corners[:, 0]
      y = corners[:, 1]
      _xrange = (np.minimum.reduce(x), np.maximum.reduce(x))
      _yrange = (np.minimum.reduce(y), np.maximum.reduce(y))
      return _xrange, _yrange
docs: Determine the range spanned by an array of pixel positions.