Figure 7a.

Diagrams of the general idea of region-based segmentation: Region-based segmentation approaches start with a seed point and then grow as they add neighboring pixels or voxels to the evolving annotation as long as the neighborhood criterion is satisfied. (a) Start of growing a region shows initial seed point (black circle) and directions of growth (arrows). (b) Growing process after a few iterations shows area grown so far (black area), current voxels being tested (gray circles), and potential directions of further growth (arrows). (c) Final segmentation (black area).