Excellent thread. I think the forum improves 100 fold with these kinds of discussions.

As for my stance on the subject... valouchufy posted a link several days back which gives a good look into art and copyright.

http://www.photosecrets.com/p14.html

From the article, copyright attorney Dianne Brinson states (and I paraphrase) that when someone creates a work of art, such as a painting, sculpture, etc., the artist is automatically protected by copyright. Being protected by the copyright, the artist has EXCLUSIVE right to "reproduce" the work of art. So if you take a picture of the artwork, you are in fact reproducing it, and in violation of the artist's copyright. So that is where I base my feeling that it is an infringement.

But that is just a technical thing as the law states. What I think bothers me is that TwoPynts' image, isn't an image of the artists's work (as the above image is), but rather a part of the artists's work, where TwoPynts has changed the composition, the tones and or lighting, the presentation. What if the artist's doesn't like it? (which I  know is doubtful, since it is a beautiful shot and I'm just being the devils' advocate) Maybe the artist thinks that the power in the piece is the flowing irregular border, as opposed to TwoPynt's rectangular border?

Make any sense?