If palette is present but not needed, do not use global palette

python-pillow · Oct 5, 2022 · e6ffbfd · e6ffbfd
1 parent ae6520c
commit e6ffbfd
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Showing 3 changed files with 9 additions and 1 deletion.
diff --git a/Tests/images/palette_not_needed_for_second_frame.gif b/Tests/images/palette_not_needed_for_second_frame.gif
diff --git a/Tests/test_file_gif.py b/Tests/test_file_gif.py
@@ -92,6 +92,12 @@ def test_l_mode_after_rgb():
         assert im.mode == "RGB"
 
 
+def test_palette_not_needed_for_second_frame():
+    with Image.open("Tests/images/palette_not_needed_for_second_frame.gif") as im:
+        im.seek(1)
+        assert_image_similar(im, hopper("L").convert("RGB"), 8)
+
+
 def test_strategy():
     with Image.open("Tests/images/chi.gif") as im:
         expected_zero = im.convert("RGB")

diff --git a/src/PIL/GifImagePlugin.py b/src/PIL/GifImagePlugin.py
@@ -274,6 +274,8 @@ def _seek(self, frame, update_image=True):
                     p = self.fp.read(3 << bits)
                     if self._is_palette_needed(p):
                         palette = ImagePalette.raw("RGB", p)
+                    else:
+                        palette = False
 
                 # image data
                 bits = self.fp.read(1)[0]
@@ -298,7 +300,7 @@ def _seek(self, frame, update_image=True):
         if self.dispose:
             self.im.paste(self.dispose, self.dispose_extent)
 
-        self._frame_palette = palette or self.global_palette
+        self._frame_palette = palette if palette is not None else self.global_palette
         if frame == 0:
             if self._frame_palette:
                 self.mode = (