I think it's a good idea, in theory, but I am going to have to think about the guidelines. For now I can just manually go in and and fix posts with too large of imagery.

I would like to say "images cannot be over 500 px" for example, but that can be hard to gauge from the forum alone. So if you are just reposting an image from the net, and have no knowledge of art software etc, it would be a pain to resize manually.

I also think its ok if the art sharing board has larger images.

So far it has been a pain to get users to use spoilers for flashing imagery and fast gifs, so I might make a post about how to use the spoiler tag..