Actually all pictures have a rating behind the scenes, we just don't show it until our algorithm feels that is has enough data to be at least semi-accurate. We could show it earlier but then you would see the rating and think, "really 8.5? no way" until it adjusts to where it should be
Pictures lose their unrated status when they have a certain number of votes within their range.... so if a picture has 30 wins against 5s and 30 loses against 9.5s, this doesn't really tell us much about their rating other than the fact they are between a 5 and a 9.5. In this case our system will put them up against 6s, 7s, and 8s while it tries to pinpoint where they should be.... it doesn't give them unrated status while it still has no idea. And if the voting is all over the place (they could have won against a 9 and then lost against a 7), then our system needs more votes to figure out what is going on.