thickenbinvol

 vol=thickenbinvol(vol,layer)

 thickening a binary volume by a given pixel width
 this is similar to bwmorph(vol,'thicken',3) except 
 this does it in 3d and only does thickening for 
 non-zero elements (and hopefully faster)

 author: Qianqian Fang, <q.fang at neu.edu>

 input:
     vol: a volumetric binary image
     layer: number of iterations for the thickenining

 output:
     vol: the volume image after the thickening

 -- this function is part of iso2mesh toolbox (http://iso2mesh.sf.net)

0001 function vol=thickenbinvol(vol,layer)
0002 %
0003 % vol=thickenbinvol(vol,layer)
0004 %
0005 % thickening a binary volume by a given pixel width
0006 % this is similar to bwmorph(vol,'thicken',3) except
0007 % this does it in 3d and only does thickening for
0008 % non-zero elements (and hopefully faster)
0009 %
0010 % author: Qianqian Fang, <q.fang at neu.edu>
0011 %
0012 % input:
0013 %     vol: a volumetric binary image
0014 %     layer: number of iterations for the thickenining
0015 %
0016 % output:
0017 %     vol: the volume image after the thickening
0018 %
0019 % -- this function is part of iso2mesh toolbox (http://iso2mesh.sf.net)
0020 %
0021 
0022 dim=size(vol);
0023 dxy=dim(1)*dim(2);
0024 fulllen=prod(dim);
0025 
0026 offs=[1,-1,dim(1),-dim(1),dxy,-dxy];
0027 for i=1:layer
0028     idx=find(vol);
0029     for j=1:6
0030         idxnew=idx+offs(j);
0031         idxnew=idxnew(find(idxnew>0 & idxnew<fulllen));
0032         vol(idxnew)=1;
0033     end
0034 end