For reference, Robert Lang is not just some origami guy who happens to use computers; he's one of the foremost origami-math guys [0] and one of the pioneers in computer-designed origami.
In his books, he typically has both detailed step-by-step instructions for each model, as well as an "overview" image that shows where all of the creases will end up on the original sheet of paper (seen in image 3 and 7 at the top of the article, as well as example [1]); it's paintings of some of these overview images that are in question. He seems to treat both those overview images and the final products as art, not mere "instructions", in prior interviews (they are actually quite useless as instructions.)
This will be a critical point in the case: do the crease overview images count as art? If so, Lang has a certain amount of say-so in how they are used.
The artist looked at his crease patterns and painted them. His work created color symmetries in a field of symmetries. The colors bring their own message to the art. Had he taken a couple of Lang's folded animals (or folded one himself or had it folded) then set it on a table with some fruit or even by itself, painted it as 'still' art, the artist has created new art.
When you paint a scene in the park, and you paint in the people who are sitting around enjoying the park, you don't have to get signed releases from them to paint them into your painting, even if someone who was at the park might recognize themselves or someone they know by a particular geometry that person has and what they were wearing that day.
My belief is that no jury in the world is going to look at Lang's actual folded stuff, and see this abstract pattern stuff, and say there was infringement.
In his books, he typically has both detailed step-by-step instructions for each model, as well as an "overview" image that shows where all of the creases will end up on the original sheet of paper (seen in image 3 and 7 at the top of the article, as well as example [1]); it's paintings of some of these overview images that are in question. He seems to treat both those overview images and the final products as art, not mere "instructions", in prior interviews (they are actually quite useless as instructions.)
This will be a critical point in the case: do the crease overview images count as art? If so, Lang has a certain amount of say-so in how they are used.
[0] he authored the proof of completeness of the Huzita-Hatori axioms: http://en.wikipedia.org/wiki/Huzita%E2%80%93Hatori_axioms [1] http://cabinetmagazine.org/issues/17/Scorpion.jpg