normal_discuss = new Image();
normal_discuss.src = "images/su_l2_hi.jpg";

high_discuss = new Image();
high_discuss.src = "images/su_l2.jpg";

normal_twitter = new Image();
normal_twitter.src = "images/su_r1.jpg";

high_twitter = new Image();
high_twitter.src = "images/su_r1_hi.jpg";

normal_threads = new Image();
normal_threads.src = "images/su_l4_hi.jpg";

high_threads = new Image();
high_threads.src = "images/su_l4.jpg";

normal_archive = new Image();
normal_archive.src = "images/su_r4.jpg";

high_archive = new Image();
high_archive.src = "images/su_r4_hi.jpg";




<!-- repeat the 4 lines above for any subsequent images. -->

function swap(){
if (document.images){
for (var x=0;
x<swap.arguments.length;
x+=2) {
document[swap.arguments[x]].src = eval(swap.arguments[x+1] + ".src");
}
}
}