Ideally images and videos are transcoded to optimal format and then several copies are created with different resolution etc. And that could be done on client or server. And if on server then there is trust involved. And then appropriate version of file has to be served depending on client needs. And then it should be content-addressable, with as little trust to third parties as possible. That's just what comes to mind, and it's already much wider scope than what blossom covers. I am not saying nip96 covers it all, but it's authors are trying to reconcile all this. Seems like a good effort to me.