You will find an applet there:
http://bigwww.epfl.ch/demo/jwatershed/index.html[
^]
Unfortunately, it only displays sizes up to 256 x 256.
Two caveats:
- the standard watershed transform is only defined for grayscale images, no color ones.
- you can be surprised by the results, especially with noisy images: the watershed transform strongly oversegments.