1. 2008/10/02H704 - DYU1 Active Contours and their Utilization at Image Segmentation Author ： Marián Bakoš Source ： 5th Slovakian-Hungarian Joint Symposium on Applied Machine Intelligence and Informatics January 25-26, 2007 Speaker ： Cheng-Jung Wu Advisor ： Ku-Yaw Chang

2. 2008/10/02 H704 - DYU 2 Outline Background Basic Types of Deformable Models Basic Definition Conclusion

3. 2008/10/02 H704 - DYU 3 Background An active contour –Image segmentation iteration result initialization

4. 2008/10/02 H704 - DYU 4 Background An active contour –Energy minimizing spline –Flexibile curve (or surface) –A set of control points Sequence of each other Straight lines –An interactive process –The user ： an initial contour The intended shape

5. 2008/10/02 H704 - DYU 5 Outline Background Basic Types of Deformable Models Basic Definition Conclusion

6. 2008/10/02 H704 - DYU 6 Basic Types of Deformable Models Deformable models –Parametric –Geometric The parametric deformable models –Curves and surfaces During deforming explicitly in parametric form –Help of some of the following formulations The formulation of minimizing energy The formulation of dynamic force

7. 2008/10/02 H704 - DYU 7 Basic Types of Deformable Models The formulation of minimizing energy –Minimization Internal ： tension or smoothness of contour Image ： high gradient → edge –Total energy minimization Internal = external energies The formulation of dynamic force –Help of force formulation Dynamic problem –External and image E.g. ： a negative gradient of potential energy function （ × ）

8. 2008/10/02 H704 - DYU 8 Basic Types of Deformable Models The geometric deformable models –Elegant solution Parametric deformable models –Curves and surfaces evolution Geometric criteria –The evolution independent Parametrization The curves and surfaces generating –The ‘level set’ of a multidimensional function Topological changes –Easy to control

9. 2008/10/02 H704 - DYU 9 Outline Background Basic Types of Deformable Models Basic Definition Conclusion

10. 2008/10/02 H704 - DYU 10 Basic Definition Snake –Internal Elastic ： curve compact ， first-order Bend ： limit its very acuminous deflections ， second-order original elastic 1 2 A B C

11. 2008/10/02 H704 - DYU 11 Basic Definition bend elastic original

12. 2008/10/02 H704 - DYU 12 Basic Definition –Image Line ， edge ， scale space –External The curve towards the object’s borders

13. 2008/10/02 H704 - DYU 13 Outline Background Basic Types of Deformable Models Basic Definition Conclusion

14. 2008/10/02 H704 - DYU 14 Conclusion Artificial vs. Real 512 5 15 Artificial initialization Real initialization

15. 2008/10/02 H704 - DYU 15 Conclusion The number of iterations –The size of the scanned surroundings Disadvantages –The initial points of the contour Dependency –Type of the picture –Computing difficulty Possible –By the use of less accurate but satisfactory methods

16. 2008/10/02H704 - DYU16 The End Thanks ~