Even if a user wants them to be 'public' ... probably need some kind of warning that images may (or, probably, are likely to) be NSFW :)
I think if users want to make their images public, then they should go through some restrictive measures, such as requiring more than 80% of user agreement (with at least 10 users participating in the vote).
If the support rate for an image later falls below 80%, then that image will enter the voting phase again.
There will be a dedicated voting page for users, so if other users do not participate in the voting, they will not be able to see the image.