Fixed GIF remapping to palette with duplicate entries#6548
Merged
hugovk merged 2 commits intopython-pillow:mainfrom Sep 21, 2022
Merged
Fixed GIF remapping to palette with duplicate entries#6548hugovk merged 2 commits intopython-pillow:mainfrom
hugovk merged 2 commits intopython-pillow:mainfrom
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Yay295
reviewed
Aug 29, 2022
Comment on lines
523
to
+527
| index = im.palette.colors[source_color] | ||
| except KeyError: | ||
| index = None | ||
| if index in used_palette_colors: | ||
| index = None |
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I think the if could be inside the try, since if there's an exception it will have already been set to None.
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I actually have a different idea of how to simplify the code. In my latest commit, I replace the try block with get().
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Addresses #6389
remap_palettecannot map multiple palette indexes to the same output index, by its very definition. It accepts a list of palette indexes that it transforms to the position in the list. There cannot be more than one palette index at a given position in the list.If a palette is supplied when saving a GIF image,
im.save("out.gif", palette=...), and that palette has duplicate entries, then the following GifImagePlugin code will try to prepare a list that maps the first of the duplicated entries to multiple locations, leaving the rest of the duplicate entries to be not strictly defined in the behaviour ofremap_palette.Pillow/src/PIL/GifImagePlugin.py
Lines 519 to 526 in ad7be55
This PR fixes that, by leaving the duplicated indexes as they are - setting
indextoNone, the next loop in GifImagePluginPillow/src/PIL/GifImagePlugin.py
Lines 527 to 532 in ad7be55
will tell
remap_paletteto map the index to itself, leaving it untouched.