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Fixed loading L mode GIF with transparency #6086

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Merged
hugovk merged 3 commits into from
Mar 10, 2022
Merged

Fixed loading L mode GIF with transparency #6086

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5c62120
Convert subsequent frames of L mode GIF to LA if transparency is present
radarhere Mar 1, 2022
e2b007f
Use transparency info key when converting to LA
radarhere Mar 1, 2022
7d32745
Allow LA to be used as a mask in paste()
radarhere Mar 1, 2022
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Binary file added Tests/images/no_palette_with_transparency.gif
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11 changes: 11 additions & 0 deletions Tests/test_file_gif.py
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Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,17 @@ def test_invalid_file():
GifImagePlugin.GifImageFile(invalid_file)


def test_l_mode_transparency():
with Image.open("Tests/images/no_palette_with_transparency.gif") as im:
assert im.mode == "L"
assert im.load()[0, 0] == 0
assert im.info["transparency"] == 255

im.seek(1)
assert im.mode == "LA"
assert im.load()[0, 0] == (0, 255)


def test_optimize():
def test_grayscale(optimize):
im = Image.new("L", (1, 1), 0)
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4 changes: 4 additions & 0 deletions Tests/test_image_convert.py
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Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,10 @@ def test_trns_l(tmp_path):

f = str(tmp_path / "temp.png")

im_la = im.convert("LA")
assert "transparency" not in im_la.info
im_la.save(f)

im_rgb = im.convert("RGB")
assert im_rgb.info["transparency"] == (128, 128, 128) # undone
im_rgb.save(f)
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19 changes: 14 additions & 5 deletions src/PIL/GifImagePlugin.py
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Original file line number Diff line number Diff line change
Expand Up @@ -167,9 +167,15 @@ def _seek(self, frame):
if self.__frame == 1:
self.pyaccess = None
if "transparency" in self.info:
self.mode = "RGBA"
self.im.putpalettealpha(self.info["transparency"], 0)
self.im = self.im.convert("RGBA", Image.Dither.FLOYDSTEINBERG)
if self.mode == "P":
self.im.putpalettealpha(self.info["transparency"], 0)
self.im = self.im.convert("RGBA", Image.Dither.FLOYDSTEINBERG)
self.mode = "RGBA"
else:
self.im = self.im.convert_transparent(
"LA", self.info["transparency"]
)
self.mode = "LA"

del self.info["transparency"]
else:
Expand Down Expand Up @@ -368,8 +374,11 @@ def load_end(self):
if self.__frame == 0:
return
if self._frame_transparency is not None:
self.im.putpalettealpha(self._frame_transparency, 0)
frame_im = self.im.convert("RGBA")
if self.mode == "P":
self.im.putpalettealpha(self._frame_transparency, 0)
frame_im = self.im.convert("RGBA")
else:
frame_im = self.im.convert_transparent("LA", self._frame_transparency)
else:
frame_im = self.im.convert("RGB")
frame_im = self._crop(frame_im, self.dispose_extent)
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4 changes: 3 additions & 1 deletion src/PIL/Image.py
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Original file line number Diff line number Diff line change
Expand Up @@ -975,7 +975,9 @@ def convert_transparency(m, v):
delete_trns = False
# transparency handling
if has_transparency:
if self.mode in ("1", "L", "I", "RGB") and mode == "RGBA":
if (self.mode in ("1", "L", "I") and mode in ("LA", "RGBA")) or (
self.mode == "RGB" and mode == "RGBA"
):
# Use transparent conversion to promote from transparent
# color to an alpha channel.
new_im = self._new(
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39 changes: 17 additions & 22 deletions src/libImaging/Convert.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1634,29 +1634,15 @@ ImagingConvertTransparent(Imaging imIn, const char *mode, int r, int g, int b) {
return (Imaging)ImagingError_ModeError();
}

if (!((strcmp(imIn->mode, "RGB") == 0 || strcmp(imIn->mode, "1") == 0 ||
strcmp(imIn->mode, "I") == 0 || strcmp(imIn->mode, "L") == 0) &&
strcmp(mode, "RGBA") == 0))
#ifdef notdef
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@radarhere radarhere Mar 1, 2022

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This seems redundant, so I've removed it.

{
return (Imaging)ImagingError_ValueError("conversion not supported");
}
#else
{
static char buf[100];
snprintf(
buf,
100,
"conversion from %.10s to %.10s not supported in convert_transparent",
imIn->mode,
mode);
return (Imaging)ImagingError_ValueError(buf);
}
#endif

if (strcmp(imIn->mode, "RGB") == 0) {
if (strcmp(imIn->mode, "RGB") == 0 && strcmp(mode, "RGBA") == 0) {
convert = rgb2rgba;
} else {
} else if ((strcmp(imIn->mode, "1") == 0 ||
strcmp(imIn->mode, "I") == 0 ||
strcmp(imIn->mode, "L") == 0
) && (
strcmp(mode, "RGBA") == 0 ||
strcmp(mode, "LA") == 0
)) {
if (strcmp(imIn->mode, "1") == 0) {
convert = bit2rgb;
} else if (strcmp(imIn->mode, "I") == 0) {
Expand All @@ -1665,6 +1651,15 @@ ImagingConvertTransparent(Imaging imIn, const char *mode, int r, int g, int b) {
convert = l2rgb;
}
g = b = r;
} else {
static char buf[100];
snprintf(
buf,
100,
"conversion from %.10s to %.10s not supported in convert_transparent",
imIn->mode,
mode);
return (Imaging)ImagingError_ValueError(buf);
}

imOut = ImagingNew2Dirty(mode, imOut, imIn);
Expand Down