Multi-level neighborhood-correlation BSpline

I’m using neighborhood correlation for registration metric and BSpline for transformation model. The images are 100x100. The neighborhood window size is 10pixel-by-10pixel. The mesh size is 10x10.

If I use 2-level registration, and set the shrink factor to be 2. The images will become 50x50 at the higher level.

Is the neighborhood window size 5pixel-by-5pixel or 10pixel-by-10pixel at the higher level?

Is the mesh size 5x5 or 10x10 at the higher level?