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FIX: handle grayscale and palette images in rotation and saturation converters - #3107
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Richard Lundeen (richlundeen) merged 4 commits intoOct 11, 2026
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Check exact PNG alpha values for palette transparency metadata, LA, and RGBA through rotation and saturation. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: a7128b5d-cac7-4687-810c-261034db97e0
Richard Lundeen (richlundeen)
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Oct 11, 2026
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Fixes #3106.
Adds
_convert_to_rgb_or_rgbato the image-to-image base: RGB/RGBA pass through, anything else becomes RGBA if it has transparency, otherwise RGB.ImageEnhance.Coloralready handles (saturation does nothing on gray anyway).JPEG output was already converted to RGB, and RGB/RGBA inputs are untouched, so existing outputs don't change.
Tests: rotation over L, LA, 1, I;16 and P (and the corner pixel gets the fill color), saturation over P, 1, I;16, L and LA. 8 of them fail on main. tests/unit/converter: 2079 passed.