var zaehler = 160;
function showImage(breite,ID) {
 if (zaehler < breite) {
  document.getElementById(ID).style.display="inline-block";
  document.getElementById(ID).style.width=zaehler+"px";
  zaehler += 20; 
  window.setTimeout("showImage("+breite+",'"+ID+"')",0);
 }
}

function hideImage(ID) {
 document.getElementById(ID).style.display="none";
 zaehler = 50;
}