Merge pull request matplotlib#30229 from meeseeksmachine/auto-backport-of-pr-30221-on-v3.10.x

Backport PR matplotlib#30221 on branch v3.10.x (BUG: fix future incompatibility with Pillow 13)

Author: timhoffm

lib/matplotlib/backends/_backend_tk.py

@@ -775,7 +775,7 @@ def _recolor_icon(image, color):
             image_data = np.asarray(image).copy()
             black_mask = (image_data[..., :3] == 0).all(axis=-1)
             image_data[black_mask, :3] = color
-            return Image.fromarray(image_data, mode="RGBA")
+            return Image.fromarray(image_data)
 
         # Use the high-resolution (48x48 px) icon if it exists and is needed
         with Image.open(path_large if (size > 24 and path_large.exists())

lib/matplotlib/backends/backend_pdf.py

@@ -1758,7 +1758,7 @@ def _writeImg(self, data, id, smask=None):
                          data[:, :, 2])
                 indices = np.argsort(palette24).astype(np.uint8)
                 rgb8 = indices[np.searchsorted(palette24, rgb24, sorter=indices)]
-                img = Image.fromarray(rgb8, mode='P')
+                img = Image.fromarray(rgb8).convert("P")
                 img.putpalette(palette)
                 png_data, bit_depth, palette = self._writePng(img)
                 if bit_depth is None or palette is None: