[bug] Resized timeline images can sometimes be quite low quality

[TheDecryptor]

Describe the bug with a clear and concise description of what the bug is.

This seems quite rare, scrolling through my timeline I can only see a few posts where it's happened, all with simple screenshots (e.g. landscape photos or such seem fine). Sometimes the resized images for display in the timeline can appear with an extremely low quality, as if they've been heavily filtered or quantized, sometimes with heavy noise or a dithering like pattern appearing.

These are some posts with images that trigger it for my server

• https://digipres.club/@foone/113950912007097926
• https://tech.lgbt/@nina_kali_nina/112518635112997562 (Specifically the GIMP screenshot)

What's your GoToSocial Version?

0.17.3+git 6f4cb2f

GoToSocial Arch

amd64 Binary

What happened?

(Had to re-encode these, GH blocks WebP files)

The message box looks particularly bad

And the GIMP image

What you expected to happen?

No random yellow smear

And no "dithering" noise

How to reproduce it?

Look at the posts in the timeline, without loading the full-size images.

Anything else we need to know?

For the record, shows in both Tusky, and Phanpy.

[tsmethurst]

Thanks! Maybe some setting we need to fiddle with in our thumbnailer.