And I'm back. Whew, that was a rough upgrade. I had to do some manual PostgreSQL surgery to get it past 0.19.3 - there were two versions of the hot_rank function so the migration script was failing.
Then I noticed the logs were full of pictrs spitting out "Read corrupted data..." and crash looping, and I spent a couple of hours trying to get it to do anything. I finally had to give up and nuke it, so I guess the few images I've posted over the years are 404s now.
I started to get discouraged and I was going to just decommission the server, but I'll try to learn my lesson and keep a closer eye on it so I can catch future problems before it's too late.
There are a million ways to do this, as have already been described in other comments. This is one more. I built https://photostripper.com/ a while back, when I was practicing building small web applications to learn different tech stacks. Lemmy is not the target audience - you folks know how to do this already, and why would you trust that I’m not keeping copies of your photos (I promise I’m not, but what is that worth?)
Anyway, I’m only mentioning it because it’s my thing and I enjoyed making it.