sct_process_segmentation: pass image to smooth_centerline
sct_process_segmentation: pass image to smooth_centerline


Former-commit-id: db700b51cf8cb7a5b9529c0d64be4ed992f4e084
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox