The drawback is that it does require 3 times interpolation. With neares-neighbour interpolation that is not obvious from the example, but it's there. Each inte

The drawback is that it does require 3 times interpolation. With neares-neighbour interpolation that is not obvious from the example, but it's there. Each interpolation step causes loss of resolution and the multiple passes might in practice make it slower due to increased memory bandwidth requirements compared to a single pass algorithm. That of course doesn't take away that it's an interesting trick to know about.