Hi Jeff
it's more complicated than that. You need a .mgz volume for every subject you want to train on that contains the labels, and an accompanying intensity volume (we usually use the norm.mgz for this purpose). Then we extract statistics to create the .gca across these subjects using mri_ca_train
cheers Bruce
On Thu, 23 Aug 2012, Jeff Thompson wrote:
From the gcaFormat freesurfer wiki page I know that: The .gca file is
composed of three volumes, which can be extracted like this:
mri_convert atlas.gca -nth 0 means.mgz mri_convert atlas.gca -nth 1 labels.mgz mri_convert atlas.gca -nth 2 priors.mgz
where:
means --> the mean intensity of the most likely label
labels --> indices of the most likely label at each voxel (indices refer to '#No.' column of $FREESURFER_HOME/FreeSurferColorLUT.txt)
priors --> the probability that that label occurs at that voxel
Is it possible to go the other way? I want to create the labels.mgz file and the others manually, and turn that into the .gca file with mri_convert.
Can this be done?
Thank you,
Jeff Thompson