Figure 2.
Illustration of the feature-based similarity metric. Mid-slices from the initial (a) and follow-up (b) CT images. The lung boundary edges are outlined in blue, while the content edges are overlaid in red; separation of the boundary (c) and content (d) edges for the initial and follow-up images; e) initial (white) and follow-up (black) lung boundary edges before registration; initial and follow-up content edges before (f) and after (g) registration.