This module quickly computes the connected 
components\index{connected components} of the 
level set\index{level set} $\{x, \; u(x) \leq g\}$, 
where $u$ is the input image and $g$ a given grey level 
(by default 128). 
We use the 8-connectedness (i.e. each point has 8 neighbors) to compute these
components, which are returned as a Fcurves structure.
The maximum number of connected 
components is limited to 10000, which theoretically allows to 
process any 200x200 image, and actually any natural image.