I'm a photographer also, and most of my work is done for clients who will eventually (or not) purchase an expensive piece of art from a gallery. I really don't care if someone "steals" my photographs from a slideshow because I'm not selling the photograph per se, I'm selling the service of providing quality photos of a very expensive piece of artwork to allow the potential buyer to make sound purchasing decisions without spending a few thousand dollars in travel to see the art in person. On photos which I do sell as photos, I use encripted watermarks which are invisible on prints, but can be detected electronically on the file itself. Only if an individual or large business would begin selling my work for profit, would I have any interest in pursuing legal action against them, and in most cases I would wait until they had already made a windfall profit to make the cost of litigation worthwhile. By and large, it's a non-issue with me. I think that worry about it is completely overblown and that there is really little one can do to prevent a dedicated theif from stealing. A couple years ago when I was in Beijing, there were perfect copies of major MicroSoft software being openly sold on the streets for the equivalent of $10 per. Same but legal software in the U.S. was selling for over $500. They were complete with manuals, holographic seals, etc., I doubt that even MicroSoft would be able to easily tell that they were copies. If a company with MicroSoft's resources can't stop this, I think we are kidding ourselves that we have any chance at all - so having someone steal a photo or two from a PTE slideshow is probably very low on my priority list of worries...