Save as RGB(A) when APNG frames have different palettes - #9870
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radarhere merged 7 commits intoAug 17, 2026
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APNG has a single PLTE, so saving P-mode frames with different palettes silently rendered every frame with the first palette. Promote the animation to RGB when palettes differ so each frame keeps its colors. Fixes python-pillow#9868
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This doesn't address the first and third enhancements. I'm still interested in merging this, but it doesn't resolve the issue completely. |
Signed-off-by: SeaStar Deng <172368758@qq.com>
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I've created DSeaStar#1 with some suggestions. |
radarhere
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Aug 15, 2026
radarhere
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Helps #9868
APNG has a single
PLTE. Saving severalPframes with different palettes previously wrote only the first frame's palette, so later frames rendered with the wrong colors.When the collected palettes differ, the animation is now saved as RGB so each frame keeps its colors. Frames that share one palette stay indexed.
Test plan
Tests/test_file_apng.py::test_apng_save_p_frames_with_different_palettesTests/test_file_apng.py::test_apng_save_p_frames_with_same_paletteTests/test_file_apng.py(49 passed)