"Register" by who or what? If ATR, then the machine is doing the "registering".

If AIT, esp backscatter, the TSA agent looking at your naked image is doing the "registering". What do you think he's looking at? Of course they render scars, as well as belly buttons and genitals and anything else you've got under your kimono. That much is clear from the low res images that have been released.

There is a reason the actual high res images and zooms have never been released. Think about it. If TSA thought that this would help their cause, do you think for a minute they would refrain from publishing a sample image?