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);

    d.getElementById("imageCaption").innerHTML = (d.getElementById(_file_name(s1))) ? 
      d.getElementById(_file_name(s1)).innerHTML
      :
      " ";
}

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