Biomedical Engineering Reference
In-Depth Information
(a)
(b)
Figure 1.
The different image modalities used in this chapter: (a) intravascular ultrasound
image; (b) intestinal capsule endoscopic image.
STOP and GO
model using these new spaces is introduced. Finally, several ex-
periments explaining the behavior of this formulation in the medical environment
are provided.
2.
ANALYSIS OF CURRENT GEOMETRIC SNAKES
Most of the current snakes define curve evolution within an energy minimiza-
tion framework. In this context, the energy functional should achieve a compro-
mise between adjusting to image features and achieving curve regularity. There
are two main tendencies for the definition of the minimizing energy.
Geodesic formulations in a contour space
The general geodesic snake formulation defines the evolution of a snake
within an energy minimization framework. In particular, the solution to
the problem is the curve Γ of minimal length in a Riemannian surface with
a metric
g
depending on the image contrast changes. It follows that the
snake, Γ, evolves according to
∂
∂t
=(
g
1
1+
|∇
·
κ
−
<
∇
g,n>
)
·
n
with
g
=
,
(1)
u
|
2
