Using sources from the public domain - who owns the rights?

[Zarathustra]

There was a case of an artist who created a piece of work from a commercial photographer. Unbeknown to the artist, the photographer recognising his work, bought his painting and proceeded to make lots of prints to sell.
The angered artist took the case to court and lost, because it was deemed the photographer (whose work was unmistakenly used) owned the rights.

Now that all seems fair and good to me, but my question is this. If a source from the public domain is used (be it a photo from NASA, an old war photo, an old master's painting etc. etc.) and the artist produces a piece based on this public domain source, are they protected from somebody then making prints of their own interpretation and selling them freely?

[CarlyHardy]

There is a link to the copyright office in the sticky thread at the top of this forum.

Art is protected for 70 years after the death of the artist (unless its extended since I last read about it). It would be better to work from personal photographs than to ever use a resource which one did not know for certain was in the public domain!

I can understand the professional photographer's reaction. :)

If you do use a reference that is in the public domain, then you have the rights to the created work, and noone should make prints from it, unless you give or sell them that right.
carly