+% EXAMPLE an example of traditional snake on U-shape image
+%
+
+% Chenyang Xu and Jerry Prince 6/17/97
+% Copyright (c) 1996-97 by Chenyang Xu and Jerry Prince
+
+ cd ..; s = cd; s = [s, '/snake']; path(s, path); cd examples;
+
+ help tradition_ex;
+ % ==== Example 1: U-shape object ====
+
+ % Read in the 64x64 U-shape image
+ %[I,map] = rawread('../images/cochon64.pgm');
+ I = imread('../images/cochon128.pgm');
+ % Compute its edge map,
+ disp(' Compute edge map ...');
+ f = 1 - I/255;
+ f0 = gaussianBlur(f,1);
+ % note: snake potential is the negative of edge map
+ disp(' Comute the traditional external force ...');
+ [px,py] = gradient(f0);
+
+ % display the results
+ figure(1);
+ subplot(121); imdisp(-f); title('snake potential');
+ subplot(122); quiver(px,py);
+ axis('square', 'equal', 'off', 'ij'); % fix the axis
+ title('traditional force');
+
+ % snake deformation
+ disp(' ');
+ disp(' Press any key to start the deformation');
+ pause;
+ figure(1); subplot(121); cla;
+ colormap(gray(64)); image(((1-f)+1)*40);
+ axis('square', 'equal', 'off');
+ disp('');
+ disp('... Now capture range is small, use closer initialization.')
+ t = 0:0.05:6.28;
+ x = 64 + 60*cos(t);
+ y = 64 + 60*sin(t);
+ [x,y] = snakeinterp(x,y,2,0.5);
+ %snakedisp(x,y,'r')
+ pause(1);
+
+ disp('... Press <CTRL>-C to stop the program at any time.');
+ for i=1:20,
+ [x,y] = snakedeform(x,y,5,0,0.1,5,px,py,5);
+ [x,y] = snakeinterp(x,y,2,0.5);
+ if i == 10
+ snakedisp(x,y,'r')
+ end
+ title(['Deformation in progress, iter = ' num2str(i*5)])
+ pause(0.5);
+ end
+
+ disp(' ');
+ disp(' Press any key to display the final result');
+ pause;
+ figure(2); clf;
+ colormap(gray(64)); image(((1-f)+1)*40); axis equal
+ snakedisp(x,y,'r')
+ title(['Final result, iter = ' num2str(i*5)]);
