Set color table fourth channel to zero for 1 and L mode when saving BMP#8889
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hugovk merged 1 commit intopython-pillow:mainfrom Jun 27, 2025
Merged
Set color table fourth channel to zero for 1 and L mode when saving BMP#8889hugovk merged 1 commit intopython-pillow:mainfrom
hugovk merged 1 commit intopython-pillow:mainfrom
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Resolves #8888
https://www.ece.ualberta.ca/~elliott/ee552/studentAppNotes/2003_w/misc/bmp_file_format/bmp_file_format.htm states that the fourth channel in a BMP color table is 'unused (=0)'.
It seems reasonable to do so when saving 1 and L mode BMPs, and makes more intuitive sense than our current strategy of setting the fourth channel to the same value as the other three.