var link = "http://server2.iranvajahan.net/images/";

Farsi0 = new Image();
Farsi0.src= link + "farsi0.gif";
Farsi1 = new Image();
Farsi1.src= link + "farsi1.gif";

var a, pic;
function change(a, pic)
{
window.document.images[a].src=pic.src;
}