def image_rescale(I, im_size, n_uv):
    """
    Rescale the obtained image
    Args:
        I (np.narray): summed up image
        im_size (int): the image size, it is to be noted that this is before the image cropping
        n_uv (int): the number of visibibility data
    """
    return I*im_size*im_size/n_uv