Ensure Image and core palettes are in sync after PA conversion - #9834
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akx wants to merge 2 commits into
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Ensure Image and core palettes are in sync after PA conversion#9834akx wants to merge 2 commits into
akx wants to merge 2 commits into
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radarhere
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Jul 30, 2026
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| im.putalpha(Image.frombytes("L", (2, 1), bytes([240, 220]))) | ||
| assert im.get_flattened_data() == ((0, 240), (1, 220)) # Matches the alpha band |
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| im.putalpha(Image.frombytes("L", (2, 1), bytes([240, 220]))) | |
| assert im.get_flattened_data() == ((0, 240), (1, 220)) # Matches the alpha band |
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They're meant to show the palette alpha isn't used.
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I consider it pretty foundational that the palette doesn't affect pixel values (without conversion). I'm not sure it needs to be tested here? We already have
Pillow/Tests/test_image_putalpha.py
Lines 28 to 33 in abb8ba0
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That test_image_putalpha segment doesn't seem to really cover the contents of the palette.
I don't see how having this here really hurts?
radarhere
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Jul 30, 2026
…s dropped) Co-authored-by: Andrew Murray <radarhere@users.noreply.github.com>
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While working on #9833, I noticed that an RGBA palette's alphas would be "resurrected" if you converted from PA to P (which retains the RGBA palette in the core im object even if the
ImagePalettewrapper is recreated), and then to RGBA.With this, the "zombie" alpha from the RGBA doesn't appear anymore.
I would suspect this is more the Do What I Mean behavior, because an RGBA palette's alpha values weren't "visible" in a PA image anyway.