deislands2d

 cleanimg=deislands2d(img,sizelim)

 remove isolated islands on a 2D image below speicified size limit

 author: Qianqian Fang (fangq <at> nmr.mgh.harvard.edu)

 input:
     img: a 2D binary image
     sizelim: a integer as the maximum pixel size of a isolated region

 output:
     cleanimg: a binary image after removing islands below sizelim

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

0001 function cleanimg=deislands2d(img,sizelim)
0002 %
0003 % cleanimg=deislands2d(img,sizelim)
0004 %
0005 % remove isolated islands on a 2D image below speicified size limit
0006 %
0007 % author: Qianqian Fang (fangq <at> nmr.mgh.harvard.edu)
0008 %
0009 % input:
0010 %     img: a 2D binary image
0011 %     sizelim: a integer as the maximum pixel size of a isolated region
0012 %
0013 % output:
0014 %     cleanimg: a binary image after removing islands below sizelim
0015 %
0016 % -- this function is part of iso2mesh toolbox (http://iso2mesh.sf.net)
0017 %
0018 
0019 img=squeeze(img);
0020 maxisland=-1;
0021 if(nargin==2) maxisland=sizelim; end
0022 
0023 islands={};
0024 
0025 cleanimg=zeros(size(img));
0026 if(sum(img(:)))
0027     img=imclose(img, strel('disk',3));
0028     islands=bwislands(img);
0029 end
0030 
0031 if(length(islands))
0032     % remove small islands of the foreground
0033     maxblock=-1;
0034     maxblockid=-1;
0035     if(maxisland<0)
0036       for i=1:length(islands)
0037         if(length(islands{i})>maxblock)
0038             maxblockid=i;
0039             maxblock=length(islands{i});
0040         end
0041       end
0042       if(maxblock>0)
0043           cleanimg(islands{maxblockid})=1;
0044       end
0045     else
0046       for i=1:length(islands)
0047         if(length(islands{i})>maxisland)
0048             cleanimg(islands{i})=1;
0049         end
0050       end
0051     end
0052 
0053     % remote small islands of the background
0054     
0055     cleanimg=imfill(cleanimg,'holes');
0056 end