I know others are saying no fan images unless explicit permission is given by everyone in it, but I think that would be next to impossible sometimes, for example group shots of cosplayers are quite common at conventions, sometimes these can include dozens of people, often people who do not know each personally, and usually the only person that is known online is the person who shared the picture on their cosplay blog, deviantart, tumblr, etc. I just think it would be next to impossible sometimes to get permission for group shots, getting permission from the person that took the photo would be fine, but every person involved would be very difficult, if not impossible sometimes, and I think Fanlore would be a poorer place for not including the images showing the history and growth of cosplay.