Just don't subscribe to subs with lots of images. That's how I do it. Although if I really really want to filter something, I'll use rss.app.

I can't do it on the main site?

You can with Dystopia, just add filtering rules for alb the image host domains. You'll still get text posts that link out to an image, but most pictures are link posts, so the domain filters will block them.

I think someone here said they could do it with Bacon Reader. I haven't experimented if you can do it with Dystopia.