def zoom_point(im, x, y, bb):
    """
    Cut out a square box from image im centered on (x,y) with half-box size bb.
    :param im: image from which box will be taken
    :param x: x coordinate of center of box
    :param y: y coordinate of center of box
    :param bb: half-box size
    :return:
    """
    return im[int(y - bb):int(y + bb), int(x - bb):int(x + bb)]