catherine96821:
I can give someone a print (or sell it to them) - they cannot then go make other prints and sell them or display them as their own. I ask about it because the original artist may or may not allow that kind of thing, I don't know. But it's important to know - not only from a legal standpoint, but from a right and wrong standpoint.
There is also the concept of "fair use." While this is a gray area, I think Catherine's use in her avatar is well within that. It is very low resolution and no one is going to use that image in leiu of the original. That doesn't mean the artwork is "hers." But, under fair use, it may not be up to the artist to decide what constitutes fair use.
A 200x200 image of the Mona Lisa used in a blog describing your trip to the Louvre is fine. Taking a photograph of the Mona Lisa and creating high quality prints for sale is not.