Biomedical Engineering Reference
In-Depth Information
Figure 11.4:
A graph of the image intensity function
I
0
(
x
) corresponding to a
“dumbbell” image (left, see also Fig. 11.5) and a graph of the function
g
(
|∇
I
0
(
x
)
|
)
(right) where a narrow valley along the edge can be observed (color slide).
not sufficient. In a noisy environment, the evolving level set can behave very
irregularly, it can be attracted to spurious edges and no reasonably convergent
process can be observed. This phenomenon is documented in Fig. 11.8 left. To
prevent such a situation, one has to regularize the evolution. A helpful regu-
larization is to add a curvature dependence to the level set flow. If evolution
Figure 11.5: Image given by the intensity
I
0
(
x
) from Fig. 11.4 (left) and the
arrows representing the vector field
−∇
g
(
|∇
I
0
(
x
)
|
) (color slide).
