-4-
¥Intra-session
registration:
3dvolreg -base 4 -heptic -clipit -zpad 4\ -prefix fred1_epi_vr \ -dfile fred1_vr_dfile \ fred1_epi+orig²-base 4 Þ Selects sub-brick #4 of dataset fred1_epi+orig as base image J(x)
²-heptic Þ Use 7th order
polynomial interpolation (my personal favorite)
²-clipit Þ Clip off negative voxels to zero
åNegative voxels are
artifacts of high-order interpolation methods
²-zpad 4 Þ Pad each target image, I(x), with layers of zero voxels 4 deep on each face prior to
shift/rotation, then strip them off afterwards
åZero padding is
particularly desireable for -Fourier
interpolation
åIs also good for
polynomial methods, since if there are large rotations, some data may get ÔlostÕ when no
zero padding if used (due to 4-way shift algorithm used for fast
rotation)
²-prefix fred1_epi_vr Þ Save output dataset
into a new dataset with the given prefix name (e.g., fred1_epi_vr+orig)
²-dfile fred1_vr_dfile Þ Save estimated movement parameters into a 1D (i.e., text) file with the
given name
åCan be plotted with
command
1dplot -volreg -dx 5
-xlabel Time Ôfred1_vr_dfile[1..6]Õ