code: def _cutout_psf(self, image, subgrid_res):
          
          self._init_mask_psf()
          return image[self._x_min_psf*subgrid_res:(self._x_max_psf+1)*subgrid_res, self._y_min_psf*subgrid_res:(self._y_max_psf+1)*subgrid_res]
docs: cutout the part of the image relevant for the psf convolution
          :param image:
          :return: