Thinning.m

function Img = Thinning(BW )
BW=~BW;

[l,m] = size(BW);
for I=1:100
 
BW = padarray(BW,[1 1],0,'both');

BW = double( BW ) ;
OutBW = BW ;
[row col] = find( BW == 1 ) ;


for i = 1 : length(row)
        indx = row(i) ;
        indy = col(i) ;
       
        Mask = [ BW(indx-1:indx+1,indy-1:indy+1)]; 
        
             if Mask(2,3) == 0 && ( Mask(1,3) == 1 || Mask(1,2) == 1)
                 b1 = 1;
             else
                 b1 = 0;
             end
             if Mask(1,2) == 0 && ( Mask(1,1) == 1 || Mask(2,1) == 1)
                 b2 = 1;
             else
                 b2 = 0;
             end
             if Mask(2,1) == 0 && ( Mask(3,1) == 1 || Mask(3,2) == 1)
                 b3 = 1;
             else
                 b3 = 0;
             end
             if Mask(3,2) == 0 && ( Mask(3,3) == 1 || Mask(2,3) == 1)
                 b4 = 1;
             else
                 b4 = 0;
             end
             b = b1 + b2 + b3 + b4 ; 
         

            Mask = logical(Mask) ;
            N1 = double( Mask(2,3) | Mask(1,3) ) + double( Mask(1,2) | Mask(1,1) ) + double( Mask(2,1) | Mask(3,1) ) + double( Mask(3,2) | Mask(3,3) );
            N2 = double( Mask(1,3) | Mask(1,2) ) + double( Mask(1,1) | Mask(2,1) ) + double( Mask(3,1) | Mask(3,2) ) + double( Mask(3,3) | Mask(2,3) ) ;
            NCondition2 = min(N1,N2) ;
            
            

            Mask = logical(Mask) ;
            Mask(3,3) = ~Mask(3,3) ;
            
            NCondition3 = ( Mask(1,3) | Mask(1,2) | Mask(3,3) ) & Mask(2,3) ;
            

             if NCondition3 == 0 && NCondition2>=2 && NCondition2<=3 && b == 1
                 OutBW(indx,indy) = 0 ;
             end            
end
OutBW = OutBW([2:end-1],[2:end-1]) ;
 BW=OutBW;



BW = padarray(BW,[1 1],0,'both');

BW = double( BW ) ;
OutBW = BW ;
[row col] = find( BW == 1 ) ;
for i = 1 : length(row)
        indx = row(i) ;
        indy = col(i) ;
        
          Mask = [ BW(indx-1:indx+1,indy-1:indy+1)]; 
        
             if Mask(2,3) == 0 && ( Mask(1,3) == 1 || Mask(1,2) == 1)
                 b1 = 1;
             else
                 b1 = 0;
             end
             if Mask(1,2) == 0 && ( Mask(1,1) == 1 || Mask(2,1) == 1)
                 b2 = 1;
             else
                 b2 = 0;
             end
             if Mask(2,1) == 0 && ( Mask(3,1) == 1 || Mask(3,2) == 1)
                 b3 = 1;
             else
                 b3 = 0;
             end
             if Mask(3,2) == 0 && ( Mask(3,3) == 1 || Mask(2,3) == 1)
                 b4 = 1;
             else
                 b4 = 0;
             end
             b = b1 + b2 + b3 + b4 ; 
         

            Mask = logical(Mask) ;
            N1 = double( Mask(2,3) | Mask(1,3) ) + double( Mask(1,2) | Mask(1,1) ) + double( Mask(2,1) | Mask(3,1) ) + double( Mask(3,2) | Mask(3,3) );
            N2 = double( Mask(1,3) | Mask(1,2) ) + double( Mask(1,1) | Mask(2,1) ) + double( Mask(3,1) | Mask(3,2) ) + double( Mask(3,3) | Mask(2,3) ) ;
            NCondition2 = min(N1,N2) ;
            
            

            Mask = logical(Mask) ;
            Mask(1,1) = ~Mask(1,1) ;
            
            NCondition3 = ( Mask(3,1) | Mask(3,2) | Mask(1,1) ) & Mask(2,1);


             if NCondition3 == 0 && NCondition2>=2 && NCondition2<=3 && b == 1
                 OutBW(indx,indy) = 0 ;
             end            
end
OutBW = OutBW([2:end-1],[2:end-1]) ;
end
Img=~OutBW;
Img=Img(101:100+l,101:100+m);