I wasn’t aware of that, I used imagemagick and I didn’t see that option when I checked the docs, but maybe that’s what image-hint was for…
Optimizing the downloadable versions is a good idea.
In my personal opinion, reducing asset quality for the web version is completely reasonable, so don’t sweat it too much 😁 (Edit: I’m on Android so I see no difference in quality really, the screen is too small for that 🤷, and even on desktop, unless you try to find faults, reasonable quality loss should be fine)
It’s probably just because I know what to look for, so it sticks out to me. But yeah, that’s a good point, especially on mobile there’s no way you’d be able to tell.