1. Liu X B, Zou B J, Sun J G. A new approach to separating touching spots in particle images [C]// Proceedings of 2004 International Symposium on Intelligent Multimedia, Video and Speech Processing, Hong Kong, China. Washington DC, USA: IEEE Computer Society Press, 2004: 133–136.
2. Lee S C, Wang Y M, Lee E T. Estimating the analog perimeter of a pre-digitized shape [C]//Proceedings of SPIE-IS&T Electronic Imaging, San Jose, CA, USA. Bellingham, WA, USA: SPIE Press, 2006, 6066: 60660D.1-60660D.9.
3. Barba J, Chan K S, Gil J. Quantitative perimeter and area measurements of digital images [J]. Microscopy Research and Technique, 1992, 21(4): 300–314.
4. Dunkelberger K, Mitchell O. Contour tracing for precision measurement [C]//Proceedings of IEEE International Conference on Robotics and Automation, Saint Louis, Missouri, USA. Silver Spring, MD, USA: IEEE Computer Society Press, 1985, 2: 22–27.
5. Gargantini I. An effective way to represent quadtrees [J]. Communications of the ACM, 1982, 25(12):905–910.