Cannot send lossless images larger than about 5MB

[sailbird]

• [ x] I have searched open and closed issues for duplicates
• [ x] I am submitting a bug report for existing functionality that does not work as intended
• [ x] I have read https://github.com/signalapp/Signal-Android/wiki/Submitting-useful-bug-reports
• [ x] This isn't a feature request or a discussion topic

---

Bug description

If you hit the "+" and try to load up a lossless image from your gallery in preparation for sending, it will just appear black if it's larger than about 5MB. If you try to send it anyway, it will refuse to send.

Steps to reproduce

1. Create a photo and save it losslessly to your gallery.
2. Try to send it to someone.

Actual result: Describe here what happens after you run the steps above (i.e. the buggy behaviour)

Image just appears as black.

Expected result: Describe here what should happen after you run the steps above (i.e. what would be the correct behaviour)

It should send as usual.

I realize that Signal has limits to message size for economic reasons, but it always recompresses lossless images to lossy images, so the same should apply regardless of how large the input image is. If the image is so utterly large than even the lossiest JPEG quality setting isn't enough to crush it below the sendable threshold, then a downscaling followed by recompression would solve that. (NB downscaling is tricky because colormaps are nonlinear, but plenty has been written about that online.) Not saying this is trivial, but it's at least superficially an actual bug.

The quick-and-dirty "fix" is simply to increase the precompression size limit from, say, 5MB to 10MB or something like that. Moore's Law could make this an easy sell with management.

If even that's too much, then at least it would be nice to see an error message or a filler "photo" which just contains an error message.

Device info

Device: Samsung S23
Android version: 14
Signal version: (latest)

[nicholas-signal]

Are you able to provide a debug log? And, if you feel comfortable, the problematic image?