-------------------------------------------
var,funct (left-click): read 3D volume into "im3"
  set inim3 <infile>
  read_images3
-------------------------------------------

The "im3:" entry (not visible on fn-F2 smaller
interface), shows the name of a tertiary volume
data set.  This data set can be used for surface
operations such as SHRINK (when "ck3rd" is
ticked).

A default startup of tksurfer from csurf (far
right "load2surf filled/T2" not ticked) will
*not* load the "im:" or "im3:" data sets.  Note
that the primary image data ("im:" entry") must 
be read before the secondary image can be read.

This can be used, for example to ignore T1 voxels
that are presumed to be blood vessels in a
corresponding T2 image, by zeroing the shrink
normal force according to a comparison between
the current "im3:" voxel value and the current
settings of $chkthird_lolim and $chkthird_hilim
("ck3:lo" and "ck3:hi" entries on next line).

To read (or re-read) that data set, click the "R"
to the right of the entry.  See R-click help for
"im:" for image format details.
