def METHOD_NAME(self, kwargs_ps, kwargs_lens=None):
    """Intrinsic brightness amplitude of point source When brightnesses are defined
    in magnified on-sky positions, the intrinsic brightness is computed as the mean
    in the magnification corrected image position brightnesses.
    :param kwargs_ps: keyword arguments of the point source model
    :param kwargs_lens: keyword argument list of the lens model(s), used when
        brightness are defined in magnified on-sky positions
    :return: brightness amplitude (as numpy array)
    """
    if self._fixed_magnification:
        source_amp = kwargs_ps["source_amp"]
    else:
        ra_image, dec_image = kwargs_ps["ra_image"], kwargs_ps["dec_image"]
        if self.k_list is None:
            mag = self._lens_model.magnification(ra_image, dec_image, kwargs_lens)
        else:
            mag = []
            for i in range(len(ra_image)):
                mag.append(
                    self._lens_model.magnification(
                        ra_image, dec_image, kwargs_lens, k=self.k_list[i]
                    )
                )
        point_amp = kwargs_ps["point_amp"]
        source_amp = np.mean(np.array(point_amp) / np.array(np.abs(mag)))
    return np.array(source_amp)