def get_offset(im, point, x_fov=1, y_fov=1):
    """
    Calculate the angular offset from centre of the point, based on given
    angular field of view for camera.
    """
    height, width = im.shape
    xpos, ypos = point

    offset_x = xpos - width/2
    offset_y = ypos - height/2

    xscale = x_fov / width
    yscale = y_fov / height

    return xscale * offset_x, yscale * offset_y