There is a very interesting discussion on Annabel Rainbow's blog about copyright law, blogs, the web, Pinterest and having your work reproduced without your knowledge or consent - see link below.
An art work really has two creative lives. The first is the process of creation between the artist and their chosen material. This can be a wonderful, frustrating, fulfilling, enriching experience, which is why so many of us indulge in it. The is second is the life of the work after completion. This can be in the realm of its interaction with its audience - hopefully creating connection, pleasure, inspiration, feeling, opinion - provoking reaction. It can also be in the physical realm, including being reproduced by the artist or other, with or without the artist's permission, with or without the artist's knowledge, with or without acknowledging the artist.
This is not a new problem. As soon as an artist reveals her work to the world, she starts to loose control of it, and art has been copied throughout history, which is why we have copyright laws. But the web, blogs and particularly Pinterest seem to be producing very gray legal areas. Most artists agree that Pinterest has brought them a larger audience, but many have been dismayed to discover their own images of their own works on sites with no reference or acknowledgement of them at all. And the worst story I have heard was of one artist finding someone had made and was selling cards of her work!
I love sharing - most of us do. I have had hours of pleasure and inspiration looking at art on the web and I admit I love it when others look at my work and leave comments. I have also been frustrated when I have found something on a pinterest board that I like, but can not find out who created it.
For this reason, I will now put my name and blog address on all my own photos. You may pin away, I will at least know that the work will be traceable back to me. Unless, of course, you can remove the name? I know I can't. I've tried, as I wasn't happy with my first attempts. I didn't succeed so its a bit intrusive for the moment. Sorry. Hopefully I'll get there.