def _scale_to_res(self):

        ax = self.axes
        shp = self._full_res.shape
        x0, x1, sx, y0, y1, sy = extract_matched_slices(ax, shp)
        # have we already calculated what we need?
        if (self._bounds is not None
            and sx >= self._sx and sy >= self._sy
            and x0 >= self._bounds[0] and x1 <= self._bounds[1]
            and y0 >= self._bounds[2] and y1 <= self._bounds[3]):
            return
        self._A = self._full_res[y0:y1:sy, x0:x1:sx]
        self._A = cbook.safe_masked_invalid(self._A)
        if self.origin == 'upper':
            self.set_extent([x0 - .5, x1 - .5, y1 - .5, y0 - .5])
        else:
            self.set_extent([x0 - .5, x1 - .5, y0 - .5, y1 - .5])
        self._sx = sx
        self._sy = sy
        self._bounds = (x0, x1, y0, y1)
        self.changed()
Change self._A and _extent to render an image whose
dataset/ETHPy150Open glue-viz/glue/glue/external/modest_image.py/ModestImage._scale_to_res