This may or may not be an issue but I believe the moderators should change the field that denotes the user posting an image so the poster would only be known to the user who posted the image and admin/mods. This would stop users being individually targeted by other users about what they post and would rate the image itself and not have their decision be influenced by who posted it. Also, users searching by username that are not their own would be disabled, except for admin/mods. I have not personally been targeted, but I know of some who have.
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EDIT: Adding an option for the poster to leave out their username so only themselves and admin/mods can see who posted it would be fine too.