Biomedical Engineering Reference
In-Depth Information
Figure 11.6: An initial ellipse driven by the vector field
−∇
g
(
|∇
I
0
(
x
)
|
) down to
the valley to find the edge in the image
I
0
(color slide).
of a curve in the normal direction depends on its curvature
k
, then the sharp
irregularities are smoothed. Such motion can be interpreted as an intrinsic dif-
fusion of the curve. A reasonable regularization term is given by
g
0
k
, where
the amount of curve intrinsic diffusion is small in the vicinity of unspurious
edges. In Fig. 11.8 (right), we present initial ellipse evolution to successful seg-
mentation result using such advection-(intrinsic) diffusion model, which was
computed by the direct method from [40]. The level set formulation of such
Figure 11.7:
The situation is more complicated in the case of a “noisy” image
(middle); we also plot a graph of its intensity
I
0
(
x
) (left) and the corresponding
surface
g
(
|∇
I
0
(
x
)
|
) (right) (color slide).
