You can send them in the original resolution by selecting "Document", then "Gallery". But yes, this requires some amount of knowledge.

That’s good knowledge though! Thanks

There is now an “HD” button when you select photos. By default this is disabled but just make sure you select it and it’s way better. Might be a new feature, I only learned about it last week or two.

Edit: Saw someone mention it a few comments down, and that it’s not quite the original. It is indeed an improvement though.

Signal offers the option to scale images or not, which seems like the best option from a user perspective (maybe not from a service provider's cost perspective).

Where is this option? I often get errors about the video being too big and then need to crop my video length to send it. Super annoying

Settings > Data and Storage on Android. Settings > Chats on desktop. It does have a 100mb limit though; you can't send long videos through chat.

You can select the compression level in settings.

Toggle the HD button before sending.

Do the experiment: it's still not the original file.

Try sending a proper DSLR camera photo using HD, it will still get damaged and "artifacted".

I believe that if you send it as a file instead of as a normal image you can send it uncompressed, (Attachements Button > Documents / Files > Select image in file picker, I guess they make this non obvious because people will gobble a ton of space even if 95% they can make do with hyper compressed blobs

yes, sending it as a file preserves 100% integrity.

it would MD5 checksum match.

I'm aware it's not the original file, rarely do I want to send the original file because it would be way too big. If you want to do that then you have to send it as a file instead.