OPT: reshape seg data
OPT: reshape seg data

Former-commit-id: 3bf0c9c955e76dfc20d48e2f5ae8acb846ea6a50
Former-commit-id: f58b1ce4afdad03a9e1f05f241ca937b0ae065c6
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox