Merge pull request #7018 from radarhere/apng

python-pillow · Mar 23, 2023 · 745f540 · 745f540
2 parents 3d4a6f7 + 0966293
commit 745f540
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Showing 3 changed files with 13 additions and 3 deletions.
diff --git a/Tests/images/blend_transparency.png b/Tests/images/blend_transparency.png
diff --git a/Tests/test_file_apng.py b/Tests/test_file_apng.py
@@ -163,6 +163,12 @@ def test_apng_blend():
         assert im.getpixel((64, 32)) == (0, 255, 0, 255)
 
 
+def test_apng_blend_transparency():
+    with Image.open("Tests/images/blend_transparency.png") as im:
+        im.seek(1)
+        assert im.getpixel((0, 0)) == (255, 0, 0)
+
+
 def test_apng_chunk_order():
     with Image.open("Tests/images/apng/fctl_actl.png") as im:
         im.seek(im.n_frames - 1)

diff --git a/src/PIL/PngImagePlugin.py b/src/PIL/PngImagePlugin.py
@@ -1003,9 +1003,13 @@ def load_end(self):
         else:
             if self._prev_im and self.blend_op == Blend.OP_OVER:
                 updated = self._crop(self.im, self.dispose_extent)
-                self._prev_im.paste(
-                    updated, self.dispose_extent, updated.convert("RGBA")
-                )
+                if self.im.mode == "RGB" and "transparency" in self.info:
+                    mask = updated.convert_transparent(
+                        "RGBA", self.info["transparency"]
+                    )
+                else:
+                    mask = updated.convert("RGBA")
+                self._prev_im.paste(updated, self.dispose_extent, mask)
                 self.im = self._prev_im
                 if self.pyaccess:
                     self.pyaccess = None