Consider all frames when selecting mode for PNG save_all#6610
Consider all frames when selecting mode for PNG save_all#6610hugovk merged 1 commit intopython-pillow:mainfrom
Conversation
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This fix seems to not be working correctly for some files. See the attached animated GIF and the resulting animated PNG. Some of the frames in the PNG file are corrupted.
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See attached a corrupted frame and the corresponding original frame (albeit with fewer colors than in the original animated GIF since there are only 256 available in a single frame).
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That actually isn't a problem related to this PR - you've found a GIF that Pillow isn't reading correctly in the first place. Run this code over your GIF, and you will see what I'm talking about. from PIL import Image
im = Image.open("in.gif")
im.seek(3)
im.save("out.gif")I'll investigate and see if I can put together a fix in a new PR. |
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Just my luck, running into 3 separate issues all with the same set of GIFs 🤦♂️ Thanks a lot! |
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I've added a commit to #6576 to fix your GIF. |
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Many thanks! |
Resolves #6608
At the moment, when saving multiple frames with PngImagePlugin, the mode of the first image is used.
Pillow/src/PIL/PngImagePlugin.py
Line 1224 in af8260e
However, this is not necessarily ideal. For a GIF, the first frame might be P, and subsequent frames might be RGB. Converting the RGB frames to P could result in loss of information.
This PR loops through the frames to be saved, checks if any are RGB, RGBA or P, and upgrades the mode accordingly.