Backport PR matplotlib#25704: FIX: don't round image sizes to pixel if meant to be unsampled

Author: ksunden

lib/matplotlib/image.py

@@ -398,7 +398,7 @@ def _make_image(self, A, in_bbox, out_bbox, clip_bbox, magnification=1.0,
         # So that the image is aligned with the edge of the axes, we want to
         # round up the output width to the next integer.  This also means
         # scaling the transform slightly to account for the extra subpixel.
-        if (t.is_affine and round_to_pixel_border and
+        if ((not unsampled) and t.is_affine and round_to_pixel_border and
                 (out_width_base % 1.0 != 0.0 or out_height_base % 1.0 != 0.0)):
             out_width = math.ceil(out_width_base)
             out_height = math.ceil(out_height_base)