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Diffstat (limited to 'synapse/rest/media/v1/thumbnailer.py')
| -rw-r--r-- | synapse/rest/media/v1/thumbnailer.py | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/synapse/rest/media/v1/thumbnailer.py b/synapse/rest/media/v1/thumbnailer.py index 07903e4017..988f52c78f 100644 --- a/synapse/rest/media/v1/thumbnailer.py +++ b/synapse/rest/media/v1/thumbnailer.py @@ -96,9 +96,14 @@ class Thumbnailer: def _resize(self, width: int, height: int) -> Image: # 1-bit or 8-bit color palette images need converting to RGB # otherwise they will be scaled using nearest neighbour which - # looks awful - if self.image.mode in ["1", "P"]: - self.image = self.image.convert("RGB") + # looks awful. + # + # If the image has transparency, use RGBA instead. + if self.image.mode in ["1", "L", "P"]: + mode = "RGB" + if self.image.info.get("transparency", None) is not None: + mode = "RGBA" + self.image = self.image.convert(mode) return self.image.resize((width, height), Image.ANTIALIAS) def scale(self, width: int, height: int, output_type: str) -> BytesIO: |