%fig924.m - Figure 9.24 Gonzales and Woods' book
% skeletonization example
% (C) 2003 by Yu Hen Hu
% created: 12/2/2003

clear all

A=[0 0 0 0 0 0 0 0 0 
   0 0 0 0 0 0 0 0 0
   0 0 1 0 0 0 0 0 0
   0 0 0 1 1 0 0 0 0
   0 0 0 1 1 0 0 0 0
   0 0 0 1 1 1 0 0 0
   0 0 0 1 1 1 0 0 0
   0 0 1 1 1 1 1 0 0
   0 0 1 1 1 1 1 0 0
   0 0 1 1 1 1 1 0 0
   0 0 1 1 1 1 1 0 0
   0 0 1 1 1 1 1 0 0
   0 0 0 0 0 0 0 0 0
   0 0 0 0 0 0 0 0 0];
figure(1),clf,colormap('gray')
B=ones(3);
x{1}=A;
for k =1:3,
   i=6*(k-1)+1;
   if k>1, x{i}=double(erode(x{i-6},B)); end
   eval(['subplot(3,6,' int2str(i) '),']),imagesc(x{i})
   x{i+1}=double(imopen(x{i},B));
   eval(['subplot(3,6,' int2str(i+1) '),']),imagesc(x{i+1})
   x{i+2}=x{i}-x{i+1};
   eval(['subplot(3,6,' int2str(i+2) '),']),imagesc(x{i+2})
   x{i+3}=zeros(size(A));
   for j=1:k,
      x{i+3}=x{i+3}+x{i+2-6*(j-1)};
   end
   eval(['subplot(3,6,' int2str(i+3) '),']),imagesc(x{i+3})
   x{i+4} = x{i+2};
   if k>1, x{i+4}=dilate(x{i+2},B,k-1); end
   eval(['subplot(3,6,' int2str(i+4) '),']),imagesc(x{i+4})
   x{i+5}=x{i+4};
   if k>1, for j=2:k, x{i+5}=or(x{i+5},x{i+4-6*(j-1)}); end, end
   eval(['subplot(3,6,' int2str(i+5) '),']),imagesc(x{i+5})
end