Shaohui Huang, Boliang Wang, Xiaoyang Huang.  Traditional Active Contour (Snake)  Gradient Vector Flow Snake (GVF Snake)  SEGMENT CT IMAGES  Edge.

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Presentation transcript:

Shaohui Huang, Boliang Wang, Xiaoyang Huang

 Traditional Active Contour (Snake)  Gradient Vector Flow Snake (GVF Snake)  SEGMENT CT IMAGES  Edge map generation  Contour initialization  Maximum force angle map

 The GVF field is defined to be a vector field V(x,y) = (u(x,y),v(x,y)), it comes from the force balance condition by replace the potential force with V(x,y), then we rewrite as

 V(x,y) is defined such that it minimizes the energy functional  where f(x,y) is the edge map of the image. GVF field can be obtained by solving following equations

 Edge map generation  Contour initialization  Maximum force angle map

 Gaussian function with sigma = 1

 Two errors with this contour  Over-segment of the liver  Caused by the blur boundary.  Error convergence inside the liver  Caused by the fake boundary.

 Canny edge detector

 The contour cannot cross the bottleneck of the liver.

 Let u, v stand for two GVF forces. Note that u, v are vectors. The angle θ formed by u, v can be calculated as:  A maximum force angle MFA at the coordinate (m,n) is defined as: