Open scy opened 1 month ago
Forgot to mention in the original report: I saw #5469 when looking for related issues which claims that this is fixed in ≥ 5.15. Maybe it's a regression?
Thanks for reporting this and for finding the related issue. We will take a look.
Using a supported version?
Overall summary
When sending images, Signal re-encodes them, often increasing file size significantly in the process. This is especially annoying if you have optimized the image's file size before sending it.
Steps to reproduce
Expected result
Since it makes sense for Signal to strip metadata (e.g. location information and serial numbers) from the image, a slight variation in file size (preferably towards the lower end) can be expected.
Actual result
When I use the "download" button to save the image that has been sent, I can see that it's now 79 K in size ("standard" setting). This is more than twice the original size. Loading both images in Python's pillow library and comparing the raw image data (
.tobytes()
, but also with.getdata()
) shows that the raw pixel data has been re-encoded, which likely also reduced the quality.Using the "high" quality setting in Signal, the image size is changed to 80 K instead. Raw image data still differs, which implies that the image has been re-encoded, too.
For good measure, I've also performed the experiment with a PNG input (275 K originally) instead.
Screenshots
Not sure whether GitHub will mangle these in some way, but these are my original input images and their SHA-256 hashes.
Signal version
7.5.1
Operating system
Debian 12 (bookworm) amd64
Version of Signal on your phone
7.7.1
Link to debug log
No response