//<![CDATA[
  var visorIMGnum=0;
  var visorPIC=new Array();

  function visorAtras(cual,mtxpics) {
    visorPIC = mtxpics
    if(visorIMGnum==0) {
      visorIMGnum=visorPIC.length-1;
    } else {
      visorIMGnum --
    }
    document.getElementById(cual).src=visorPIC[visorIMGnum].src;
  }

  function visorAdelante(cual,mtxpics) {
    visorPIC = mtxpics
    if(visorIMGnum==visorPIC.length-1) {
      visorIMGnum=0;
    } else {
      visorIMGnum ++;
    }
    document.getElementById(cual).src=visorPIC[visorIMGnum].src;
  }
//]]>