html代码大全 如何让一张图片有浅到深的渐变

<SCRIPT language=javascript1.2> 

<!-- 

function high(which2){ 

theobject=which2 

highlighting=setInterval("highlightit(theobject)",50) 

} 

function low(which2){ 

clearInterval(highlighting) 

which2.filters.alpha.opacity=40 

} 

function highlightit(cur2){ 

if (cur2.filters.alpha.opacity<100) 

cur2.filters.alpha.opacity+=10 

else if (window.highlighting) 

clearInterval(highlighting) 

} 

</script> 

<img onm ouseout=low(this) onm ouseover=high(this) style="FILTER: alpha(opacity=40)"src="logo.gif" >