Modulation tutorial

Simple illustration of the Jacobian determinant as a geometric scaling factor

This graphical tutorial is intended to help neuro-imaging researchers from non-mathematical backgrounds to understand the so-called "modulation" process in voxel-based morphometry. This preserves volume (locally and globally) in spatially normalised (warped) images by multiplying the original probabilistic segmentation values by the determinant of the Jacobian matrix of the geometric warp at each voxel.