how do I prevent my pictures from being photographed

[Claws Kondor]

How do I prevent someone from photographing wall mounted art that was created by me?

[Marigold Devin]

You cannot, except by not putting it on display at all. Even if you could have a setting that stopped people taking photographs, people can always make screenshots. If your art is so precious to you, maybe you need to consider displaying it on a website with "specimen" placed over it, so that people have to buy it.

[Mags Indigo]

I really don't think it is possible to prevent anyone from photographing anything or anyone in SL. If your artwork shows up for sale somewhere you could file an 'Abuse Report' and take it further. But no - I don't think there is anything you can practically do to prevent anyone from taking a photo of it. Sorry about that.

[George Orellana]

You can't. The best thing you can do is make a policy in your sim that no snapshots are to be taken and if they do they will get banned from your sim. Then use Phoenix viewer, as it will tell you who has taken a snapshot. Note that even then there is a way to circumvent this with a simple screenshot. Bottom line is if you do not want your art to be photographed then don't put it up.

[Lyra Blackthorne]

You cannot stop them from taking pics but you can make it undesirable to do so; place a large watermark over the image. 

[Venus Petrov]

I have been in a gallery where a distinctive watermark was put over the art to dissuade just this type of activity.  Good luck!