You want to be able to show your screenshots from your screenshots folder on a printbrick of those dimensions?
To do that other people in the server would have to download every one of your screenshots to view them, bearing in mind that it takes about five seconds to download a 256x256 picture. (1024*768 is 81/2 times larger) It also would only work if you are hosting the server, as it is impossible for players to upload new files to a server while it is running (technically you can, very laggy and slow), so it loses a lot of functionality.
It's possible but I don't think it would have much use.