I have had problems lately with Wikipedians of uploading large numbers of images from my library to the Wikipedia site. Although the photos are original, they are of museum art works which they claim as "public domain." Is there any way to discourage this? Getting an image removed from Wikipedia once uploaded is nearly impossible. At the moment I've placed them all as backgrounds behind spacer files. But naturally I loose all the Google images traffic using this method. Any other suggestions on how to keep possession of the photos?
I know it's not a direct solution to your problem but have you thought about watermaking your images with your site name?
contact Wikipedia not the users, they' have a section for this sort of stuff. If you took the pictures or you have the rights to those pictures, there legally yours and regardless of whether the item you took a picture of was public domain - the picture remains your possession and your copyrighted work.
If you had permission to take pictures of the art work, and some one uses them, then they have also violated the copyright of the artist or the museum. Let them know what is happening. If you didn't get permission, then you have no standing at all because you are doing the same thing.
Assuming we are talking about 2D works of art that are in the public domain the courts agree: http://www.law.cornell.edu/copyright/cases/36_FSupp2d_191.htm Actually it is fairly simple if you can show they are copyvios see: http://en.wikipedia.org/wiki/Wikipedia:Contact_us/Article_problem/Copyright You had better have a fairly solid cases because the people on the receiving end of those emails have fairly good understanding of the relevant parts of US copyright law
Not always true: http://www.law.cornell.edu/copyright/cases/36_FSupp2d_191.htm or the wikipedia article on the subject: http://en.wikipedia.org/wiki/Bridgeman_Art_Library_Ltd._v._Corel_Corporation
If you are allowed then just put a watermark on those photos, that way you will get some traffic as well.
It's interesting that UK and US law appear to be at odds over this issue. In terms of discouraging Wikipedians and others from using your images, I would say that watermarking is the best option, rather than going at this from a legal standpoint. It's probably a grey area, in spite of the Corel vs. Bridgeman ruling. But in practical terms, adding a watermark may prevent some copying, and if it doesn't it will at least get you some publicity for your efforts.