function _file_name(s)
{return (s.lastIndexOf("/") == -1) ? s : s.substr(s.lastIndexOf("/")+1);}

function _file_path(s)
{return (s.lastIndexOf("/") == -1) ? '' : s.substr(0, s.lastIndexOf("/")+1);}

function swap_images(ilarge, ismall)
{
    d=document;
    var s1=d[ismall].src, s2=d[ilarge].src;
    d[ismall].src=_file_path(s1)+_file_name(s2);
    d[ilarge].src=_file_path(s2)+_file_name(s1);
}

function setImage(ilarge, ismall)
{
    d=document;
    var s1=d[ismall].src, s2=d[ilarge].src;
    d[ilarge].src=_file_path(s2)+_file_name(s1);
}