GRERODE Morphological erosion on graph.

   LBL2 = grErode(EDGES, LBL1)
   Each label of the graph is assigned the smallest label of its
   neighbours, or it keeps the same label this one is smaller.

   Example
   grErode

   See also
   grDilate, grOpen, grClose

 ------
 Author: David Legland
 e-mail: david.legland@grignon.inra.fr
 Created: 2006-01-20
 Copyright 2006 INRA - CEPIA Nantes - MIAJ (Jouy-en-Josas).

Package: matgeom