var banner = new Array();

banner[0]='https://img4.hostingpics.net/pics/970597panicroomv2psd368.png';
banner[1]='https://img15.hostingpics.net/pics/274826panicroomv3fondu.png';
banner[2]='https://img15.hostingpics.net/pics/757913panicroomv1fondu.png';

document.getElementById('i_logo').src= banner[Math.floor(Math.random()*banner.length)];