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Fix ImagePalette colors for raw palettes #9821

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Fix ImagePalette colors for raw palettes #9821

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bf508a7
Fix ImagePalette colors for raw palettes
Jul 23, 2026
84571ab
Use core palette conversion for raw colors
Jul 24, 2026
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14 changes: 14 additions & 0 deletions Tests/test_imagepalette.py
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,20 @@ def test_sanity() -> None:
assert len(palette.colors) == 256


def test_colors_rawmode() -> None:
palette = ImagePalette.raw(
"BGRX",
bytes.fromhex("00000000ffffff000000ff0000ff0000ff000000"),

@radarhere radarhere Jul 24, 2026

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Suggested change
bytes.fromhex("00000000ffffff000000ff0000ff0000ff000000"),
"BGRX", (0, 0, 0, 0, 255, 255, 255, 0, 0, 0, 255, 0, 0, 255, 0, 0, 255, 0, 0, 0)

This makes it much easier to read, swap around the channels in your head, and understand how the BGRX values are transformed into the expected RGB values.

)
assert palette.colors == {
(0, 0, 0): 0,
(255, 255, 255): 1,
(255, 0, 0): 2,
(0, 255, 0): 3,
(0, 0, 255): 4,
}


def test_reload() -> None:
with Image.open("Tests/images/hopper.gif") as im:
original = im.copy()
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12 changes: 10 additions & 2 deletions src/PIL/ImagePalette.py
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Original file line number Diff line number Diff line change
Expand Up @@ -62,10 +62,18 @@ def palette(self, palette: Sequence[int] | bytes | bytearray) -> None:
@property
def colors(self) -> dict[tuple[int, ...], int]:
if self._colors is None:
palette = self.palette
if self.rawmode:
from . import Image

im = Image.core.new("P", (0, 0))
im.putpalette(self.mode, self.rawmode, palette)
palette = im.getpalette(self.mode, self.mode)

mode_len = len(self.mode)
self._colors = {}
for i in range(0, len(self.palette), mode_len):
color = tuple(self.palette[i : i + mode_len])
for i in range(0, len(palette), mode_len):
color = tuple(palette[i : i + mode_len])
if color in self._colors:
continue
self._colors[color] = i // mode_len
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