True. The fact of locality in real-world 2D images means you can predict a pixel's value by picking any neighboring pixel, or indeed any nearby pixel, with wors

True. The fact of locality in real-world 2D images means you can predict a pixel's value by picking any neighboring pixel, or indeed any nearby pixel, with worsening performance with L2 distance. There's no reason I can think of to prefer a direction, except for convenience in the data structure.