Fig. 1. Experimental setup. (a) Front view; (b) top view

Fig. 2. Various forms of bubble images

Fig. 3. Bubble projection image segmentation

Fig. 4. Edge extraction process. (a) Original image; (b) pre-processing; (c) Ostu partition; (d) edge swell; (e) region segmentation; (f) Canny edge extraction

Fig. 5. Segmentation and reconstruction of overlapping bubbles

Fig. 6. Scan bubble edge point

Fig. 7. Schematic of edge gradient

Fig. 8. Comparison of edge extraction between SEE and TSED. (a) 623 lx; (b) 442 lx; (c) 276 lx

Fig. 9. Influence of parameter variation on HSDM calculation

Fig. 10. Bubble volume of different methods at different stirring rates

Fig. 11. Trend graph of measurement of bubble surface area