def computeRange(corners):
    """ Determine the range spanned by an array of pixel positions. """
    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
Determine the range spanned by an array of pixel positions.