| Very simple question: Can anybody tell me what exactly the 'N vox'
| values in the segmentation Output window mean, where the difference
| between these values and the N pix values in SPM96 is and finaly if
| there is any conection between these Values and the actual Number of
| Voxels in the brain which are GM/WM/liquor.
The segmentation estimates the classification from a subset of voxels
within the image volume. N vox is simply the proportion of these voxels
that is classified as the different tissue types. In SPM96, N pix was
the number of voxels within the subset, that were classified as the
different types.
The values are loosely related to the number of GM/WM/CSF voxels in
the brain, but a better indication would be obtained by integrating the
contents of the *_seg*.img files:
V = spm_vol(spm_get(1,'*_seg*.img'));
vol = 0;
for i=1:V.dim(3),
img = spm_slice_vol(V,spm_matrix([0 0 i]),V.dim(1:2),0);
vol = vol + sum(img(:));
end;
fprintf('%g voxels, %g litres\n', vol, vol*det(V.mat(1:3,1:3))*1e-6);
Regards,
-John
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