var banner = new Array();

banner[0]='https://img11.hostingpics.net/pics/121537BASEHEADERcopie.png';
banner[1]='https://img11.hostingpics.net/pics/683712BASEHEADER2copie.png';
banner[2]='https://img11.hostingpics.net/pics/399898BASEHEADER3copie.png';
banner[3]='https://img11.hostingpics.net/pics/556479BASEHEADER4copie.png';

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