Hermann & Irina
"Ah," she said with a smile then turned them back to the piece he'd noticed. "The perspective is slightly off, as if the artist changed position mid-way through the piece. It gives the impression that the viewer is moving depending on what point of the image they are looking at."
Irina tilted her head as she regarded the sketch. "I can't say if it was on purpose, but it does make it unique. I rather doubt anyone else could duplicate it without such subtlety."