if(document.images) {
pics = new Array(); 
pics[1] = new Image();
pics[1].src = "/images/bt-home1.gif"; 
pics[2] = new Image();
pics[2].src = "/images/bt-home2.gif";
pics[3] = new Image();
pics[3].src = "/images/bt-about1.gif"; 
pics[4] = new Image();
pics[4].src = "/images/bt-about2.gif";
pics[5] = new Image();
pics[5].src = "/images/bt-sp1.gif"; 
pics[6] = new Image();
pics[6].src = "/images/bt-sp2.gif";
pics[7] = new Image();
pics[7].src = "/images/bt-testi1.gif";
pics[8] = new Image();
pics[8].src = "/images/bt-testi2.gif";
pics[9] = new Image();
pics[9].src = "/images/bt-gall1.gif";
pics[10] = new Image();
pics[10].src = "/images/bt-gall2.gif";
pics[11] = new Image();
pics[11].src = "/images/bt-ov1.gif";
pics[12] = new Image();
pics[12].src = "/images/bt-ov2.gif";
pics[13] = new Image();
pics[13].src = "/images/bt-ctc1.gif";
pics[14] = new Image();
pics[14].src = "/images/bt-ctc2.gif";
pics[15] = new Image();
pics[15].src = "/images/bt-tt1.gif";
pics[16] = new Image();
pics[16].src = "/images/bt-tt2.gif";
pics[17] = new Image();
pics[17].src = "/images/bt-new1.gif";
pics[18] = new Image();
pics[18].src = "/images/bt-new2.gif";
}

function changer(from,to) {
if(document.images) {
document.images[from].src = pics[to].src;
}
}