(a) An image of HeLa cells marked with COPII at one-fourth the original resolution. (b) Hand-segmented masks (green, pink, yellow and red), together with hand-drawn seeds (light gray). (c) Seeded watershed algorithm initialized with hand-drawn seeds and overlaid on the hand-segmented masks for comparison. (The excess areas marked by seeded watershed algorithm are indicated in light pink, blue, green and yellow.) Area similarity is AS=82.48%. (d) Active mask algorithm initialized with random seeds overlaid on the hand-segmented masks. Area similarity is AS=91.80%. (e) Active mask algorithm initialized with hand-drawn seeds overlaid on hand-segmented masks. Area similarity is AS=91.80%.