Resampling algorithm used on client-side thumbnailing for e2e images is ugly

[ara4n]

Here's a really good example of awful image quality: combination of not using hidpi and using nearest-neighbour(?) resampling:

keywords: filtering, resample, resize, lanczos, scaling, thumbnail

[uhoreg]

Another example, which is probably more obvious. (from https://matrix.to/#/!UCnwUWwIKhcpaPTHtR:sw1v.org/$14873254196120DQVBt:matrix.org) Definitely looks like nearest-neighbour there.

[ara4n]

The Right Solution(tm) to this is probably https://github.com/nodeca/pica

[ara4n]

bumping up the severity as it's not really 'tolerable' to have spectacularly ugly thumbnails in an e2ee-by-default world. it's a concrete bug.

[chronos1970]

I'd like to add that the avatar shown in the call panel does also have a very bad quality. However the avatar shown on the right panel doesn't seem to suffer from the same issue for some reason.

[t3chguy]

That's unrelated, avatars aren't encrypted @chronos1970. Please file a relevant issue.

[ara4n]

It's still looking awful:

original being: