code: def transform_grid_to_reference_frame(self, grid):
          
          transformed = np.subtract(grid, self.centre)
          return transformed.view(TransformedGrid)
docs: Transform a grid of (y,x) coordinates to the reference frame of the profile, including a translation to \
          its centre.
  
          Parameters
          ----------
          grid : ndarray
              The (y, x) coordinates in the original reference frame of the grid.