document.body.onload = copyright('/');

function copyright(arrel) {
    var copyr = document.getElementById('copyright');
    var imatge = copyr.getElementsByTagName('img')[0];
    copyr.onmouseover = function() { imatge.src = arrel + "img/copyright1.gif" };
    copyr.onmouseout = function() { imatge.src = arrel + "img/copyright.gif" };
}