  Mathematical Morphology proposes to extract shapes from images as connected
components of level sets. These methods prove very suitable for shape
recognition and analysis. We present a method to select the perceptually
significant (i.e., contrasted) level lines (boundaries of level sets), using
the Helmholtz principle as first proposed by Desolneux et al. Contrarily to the
classical formulation by Desolneux et al. where level lines must be entirely
salient, the proposed method allows to detect partially salient level lines,
thus resulting in more robust and more stable detections. We then tackle the
problem of combining two gestalts as a measure of saliency and propose a method
that reinforces detections. Results in natural images show the good performance
of the proposed methods.
