Usage: @T1scale <-T1 T1vol> <-PD PDvol>

Fix bias field shading in T1 by scaling it with PD image.
You can also get a decent result even without the PD volume.

   -T1 T1vol: The T1 volume
   -PD PDvol: The PD volume (aligned to T1)
   -odir ODIR: Directory where output gets dumped.
              Default is T1scale/
              ODIR will contain multiple volumes with the one
              of most interest being T1.uni+orig

         Script will reuse existing  volumes

   -align: Align PD volume to T1. Script assumes volumes are in
           close alignment. With this option, output PD+orig volume
           will be in alignment with T1+orig.
        Without this option, PDvol is assumed in alignment with T1vol
   -mask MVOL: Create mask for the output
         If not specified, the script will generate one with
         3dAutomask on fattened PDvol.
   -head_mask: Create mask using 3dSkullStrip's -head option.
   -unmasked_uni: Do not apply masking to uniformized volume (default)
                  You can mask the output after you decide which mask
                  is best. Here is an example with smask:

                  3dcalc -a T1.uni+orig. -b smask+orig. \
                         -expr 'step(b)*a' -prefix T1.uni.m
   -masked_uni: Apply masking to uniformized volume

   -echo: Set echo
   -help: this message

Global Help Options:

   -h_web: Open webpage with help for this program
   -hweb: Same as -h_web
   -h_view: Open -help output in a GUI editor
   -hview: Same as -hview
   -all_opts: List all of the options for this script
   -h_find WORD: Search for lines containing WORD in -help