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Dear SPMers I’ve been trying to normalize SPGR T1W images (256x256x106 0.94mmx0.94mmx1.50mm) using SPM5 VBM segmentation function (native+modulated+unmodulated). I use matlab 7.1 in Linux with the update 456. I wanted to compare the differences between “with” and “without” non-linear transformation, so I turned on non-linear transformation by setting DCT cutoff=25 and turn it off by setting it to DCT cutoff=inf. All of other parameters are set to the default values. I was expecting affine component, which was extracted from ”_seg_sn.mat”, to be the same between the two ways, but they turn out to be different. I appreciate if anyone has an explanation for this. ”_seg_sn.mat” DCT cutoff=25 2.1310 -0.0608 0.0777 28.1888 0.0796 2.0519 -0.5784 15.4785 -0.0364 0.3629 1.2825 -13.4118 0 0 0 1.000 DCT cutoff=inf 2.1315 -0.0478 0.0745 27.6491 0.0660 2.0546 -0.5704 15.9588 -0.0369 0.3577 1.2839 -12.8985 0 0 0 1.000 Thanks, Hedok Lee