  We propose here a proof of existence of a minimizer of a segmentation
functional based on a priori information on target shapes, and formulated with
level sets. The existence of a minimizer is very important, because it
guarantees the convergence of any numerical methods (either gradient descents
techniques and variants, or PDE resolutions) used to solve the segmentation
model. This work can also be used in many other segmentation models to prove
the existence of a minimizer.
