For me, the picture does not tell the whole story.
You should provide a input, where the picture is linked to more information explaining the promotion that was done. It might contain contact information for people who wants to comment or supply additional
support to these people.
At this stage anyone can take photo's posted on the internet and post it there with a BTC address and get some FREE money for doing nothing.
You might even add a option, where people can add a link to a youtube video, if they want to explain what they have done.