Here's the patent: http://www.google.com/patents/EP1868820B1?cl=en

Make sure to give those immoral fucks not the slightest bit of income.

Maybe not the idea itself but a method to print it?

Nope.

Claim 1: white-ish lines on light grey paper.

Claim 2: As above, but more closely matching white and grey.

Claim 3: Either of the above but with a slightly colored paper instead of gray.