var popup;

function PopupPic(pfad, breite, hoehe)
{      
var abst_o;
var abst_l;
var werte;

  abst_o = (screen.availHeight - hoehe) / 3;
  abst_l = (screen.availWidth - breite) / 2;
  abst_o = Math.ceil(abst_o);
  abst_l = Math.ceil(abst_l);
  abst_o = Math.abs(abst_o);
  abst_l = Math.abs(abst_l);
  werte = "width="+breite+",height="+hoehe+",screenX="+abst_l+",screenY="+abst_o+"";
  popup = window.open(pfad, "Bildfenster", werte);
  popup.focus();
  window.popup.onBlur = window.popup.close;
}