function zfilter(im)
clf;
colormap(gray(255));
subplot(3,3,1);
image(im);
title('Original Image');

for i=1:8,
  subplot(3,3,i+1);
  z15 = zucker(15,( (i-1)*pi/8));
  resz = filter2(z15,im);
  resz = resz * (255 / max(max(resz)));
  image(resz);
  title(['Edge Map ', sprintf('with %d pi/8',i-1)]);
end;
return;

