Fix for #653 - animated gifs with mode "P" errors

easy_thumbnails/processors.py

@@ -55,7 +55,12 @@ def apply_to_frames(self, method, *args, **kwargs):
         new_frames[0].save(
             write_to, format=self.im.format, save_all=True, append_images=new_frames[1:]
         )
-        return Image.open(write_to)
+        to_return = Image.open(write_to)
+        # mode changes are not always correctly applied, probably due to the BytesIO and save workaround
+        # so force them here.
+        if to_return.mode != new_frames[0].mode:
+            to_return = to_return.convert(new_frames[0].mode)
+        return to_return
 
     def __getattr__(self, key):
         method = getattr(self.im, key)

easy_thumbnails/tests/test_animated_formats.py

@@ -3,6 +3,8 @@
 from easy_thumbnails import processors
 from unittest import TestCase
 
+from easy_thumbnails.files import get_thumbnailer
+
 
 def create_animated_image(mode='RGB', format="gif", size=(1000, 1000), no_frames=6):
     frames = []
@@ -81,3 +83,10 @@ def test_background(self):
         # indeed processed?
         self.assertEqual(frames_count, processed_frames_count)
         self.assertEqual(processed.size, (1000, 1800))
+
+    def test_gif_with_mode_p(self):
+        with open("easy_thumbnails/tests/files/animated_mode_p.gif", "rb") as im:
+            t = get_thumbnailer(im, "easy_thumbnails/tests/files/animated_mode_p.gif")
+            # should not fail because of wrong mode
+            # https://github.com/SmileyChris/easy-thumbnails/issues/653
+            t.get_thumbnail({'size': (500, 50), 'crop': True})