compressed prototype file

i have created an image gallery from
http://www.lokeshdhakar.com/projects/lightbox2

the prototype.js file from this website that i downloaded is quite big

i need a compressed version of this prototype.js file i tried searching for few compresses versions but when i use these files i do not get the effect that this plugin creates when an image is clicked

please advice where i can get a compressed version so that i can use a small javascript file and also get the gallery effect

thanks