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Re: Normalising individual voxels

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Thu, 28 Aug 2008 10:15:51 +0100

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 ```For inverse normalisation I have amended line around 471 of spm_write_sn.m to of = bb(1,:)-vox; and comment out lines around 453 % bb(:,1) = round(bb(:,1)/vox(1))*vox(1); % bb(:,2) = round(bb(:,2)/vox(2))*vox(2); % bb(:,3) = round(bb(:,3)/vox(3))*vox(3); which seem to produce results without the shifting effect. Simon -----Original Message----- From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] On Behalf Of Joao Pereira Sent: 27 August 2008 23:46 To: [log in to unmask] Subject: [SPM] Normalising individual voxels Hello, I was successful in implementing the voxel normalisation procedure (As  described in this mailing list, using Utils -> Deformations ->  Composition -> Inverse), in order to find the position of a voxel in  stereotactic space given it's location in native space. The issue is that, in some volumes, when I visualise the results,  there seems to be a systematic shift (~4 voxels) on the y axis from  where I would expect to find the normalised voxel. I'm extracting the coordinates from native space ([x y z] in voxel  position), and using the N.dat from the y_* deformation file  (N.dat(x,y,z,:,:) = [x' y' z'] - point in standard space in mm). In  order to convert the result to voxel positions, I'm using: M = inv(spm_get_space("mwc file")) output = [x' y' z']*M(1:3,1:3) + M(1:3,4) Any ideas as to what is wrong, or is it just a display issue? Thank you for your help! Joao```