region_shrinking.hxx

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/*               Copyright 2012-2013 by Ullrich Koethe                  */
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#ifndef VIGRA_REGION_SHRINK_HXX
#define VIGRA_REGION_SHRINK_HXX

#include "multi_array.hxx"
#include "multi_gridgraph.hxx"
namespace vigra {


    template<unsigned int DIM, class LABEL_TYPE,class LABEL_TYPE_OUT>
    void regionShrinking(
        MultiArrayView<DIM,LABEL_TYPE>     labels,
        const size_t shrinkNpixels,
        MultiArrayView<DIM,LABEL_TYPE_OUT> shrinkedLabels
    ){
        shrinkedLabels = labels;

        typedef GridGraph<DIM, undirected_tag> Graph;
        typedef typename Graph::Node Node;
        //typedef typename Graph::Edge Edge;
        typedef typename Graph::NodeIt graph_scanner;
        typedef typename Graph::OutArcIt neighbor_iterator;

        const Graph g(labels.shape());

        // INITAL LOOP
        for (graph_scanner n(g); n != lemon::INVALID; ++n){
            const Node node(*n);
            for (neighbor_iterator arc(g, node); arc != lemon::INVALID; ++arc){
                const Node otherNode = g.target(arc);

                if(labels[node]!=labels[otherNode]){
                    shrinkedLabels[node]=0;
                    shrinkedLabels[otherNode]=0;
                }
            }
        }

        MultiArray<DIM,bool> visited(labels.shape());
        for(size_t r=0;r<shrinkNpixels-1;++r){
            std::fill(visited.begin(),visited.end(),false);
            for (graph_scanner n(g); n != lemon::INVALID; ++n){
                const Node node(*n);
                if(!visited[n] && shrinkedLabels[node]==0){
                    for (neighbor_iterator arc(g, node); arc != lemon::INVALID; ++arc){
                        const Node otherNode = g.target(arc);
                        shrinkedLabels[otherNode]=0;
                        visited[otherNode]=true;
                    }
                }
            }
        }
    }


} // end namespace vigra

#endif // VIGRA_REGION_SHRINK_HXX