RegSeg is a simultaneous segmentation and registration method that uses active contours without edges (ACWE) extracted from structural images. The contours evolve through a free-form deformation field supported by the B-spline basis to optimally map the contours onto the data in the target space.
In the registration pipeline with real brains, there seems to be a problem with the brain mask. Looks like a flip in X is happening.
There are two potential reasons for this: