why on earth would you want to be a part of an imageboard? A private one for a small group of people would be ok, but a lot of the appeal to anonymous boards is that somebody can just stop by and say something of quality real quick and bounce without the registration process.
If you really want an image with your discussion, just link to it here. All of that weird "meme" garbage (are those really memes or just shitty propoganda?) isn't worth a thing, and beyond a lack of userbase, the future- as sad as it may be, is right are your fingertips. I don't see it getting much better than this for a public anonymous text board.