Where (if at all) does intensity non-uniformity (INU) correction occur?

[TPDeramus]

Hi experts.

Admittedly just found out about this tool, but as I was reading both the code and the OHBM paper about it, and I can't seem to locate in the description where this is occuring.

Does this approach require INU corrections or is there a place in the code where I'm just not seeing it?

Thank you in advance.