[Freesurfer] converting tkmedit images

Hi Experts!

I am trying to montage snapshots from tkmedit. the output of my tcl scripts are tiff. to save ink i am trying to change the background to white before concatenating them into larger images.

the following works fine with tksurfer but does NOT work with tkmedit generated tiffs -- i am guess i may have to add flags ? but not sure which:

convert -fill white -opaque black file.tif file.jpg

if convert is not the right executable for the tkmedit *tif images please let me know - was under the impression there is no special masking in any tcl generated tiffs with either tksurfer or tkmedit so not sure why this is not workink on the solid black areas

best regards polly