% morphdemo.m
% demonstration of morphological operators
% (C) 2003 by Yu Hen Hu
% created: 11/21/2003
%

clear all
load p64int.txt; % 64 x 64 gray scale image
V=[80:168];
x=ones(size(p64int))-ismember(p64int,V);
figure(1),clf,
subplot(231),imagesc(x),colormap('gray')

% dialation and erosion
disp('***********************************')
disp('0 - square (default)');
disp('1 - circle');
disp('2 - lower triangle');
chos=input('Enter your structure element choice: ');
if isempty(chos), chos=0; end
switch chos
case 0 % rectangle structure element
   dimen=input('enter dimension of the rectangle structure element (default 3): ');
   if isempty(dimen), dimen=3; end
   S=ones(dimen);
case 1 % circle element
   r=input('enter radius of the circle structure element (default = 2): ');
   if isempty(r), r=2; end
   S=zeros(2*r+1); % a square of 2r+1
   for i=1:2*r+1,
      for j=1:2*r+1,
         if (i-r-1)^2+(j-r-1)^2 <=r^2; S(i,j)=1;
         end
      end
   end
case 2% triangular shape
   S=[1 0 0; 1 0 0; 1 1 1];
end

figure(2),clf,imagesc(S);,colormap('gray')

disp('Dilation and Erosion')
% using command dilate and erode
y1=dilate(x,S);
figure(1),subplot(232),imagesc(y1),title('dilation')

y2=erode(x,S);
figure(1),subplot(233),imagesc(y2),title('erosion')

pause
disp('Opening and Closing')
% opening and closing
y3=dilate(y2,S);  % opening
figure(1),subplot(234),imagesc(y3),title('opening')

y4=erode(y1,S); % closing
figure(1),subplot(235),imagesc(y4),title('closing')

pause
% boundary extraction
beta=x-double(y2);
figure(1),subplot(236),imagesc(beta),title('boundary extraction')