function initGray(){
  for(var i=0,c=document.getElementsByTagName('span');i<c.length;i++)
    if(c[i].className=='gray'&&c[i].getElementsByTagName('img').length==1){
      c[i].onmouseenter=function(){doTrans(this,false);};
      c[i].onmouseleave=function(){doTrans(this,true);};
    }
  function doTrans(ele,bgray){
    ele.filters[0].apply();
    ele.getElementsByTagName('img')[0].filters[0].enabled=bgray;
    ele.filters[0].play();
  }
}
if(window.attachEvent)
  window.attachEvent('onload',initGray);