图片上出现明暗变化的效果

<style>
<!--

#spotlight{
filter:light
}

-->
</style>
<img id="spotlight" speed="50" src="photo/456.gif"><BR>
<a href="www.1stscript.com"><img id="spotlight" speed="100" src="photo/exchangelogo.gif" border=0></a>
<script language="JavaScript1.2">

if (document.all&&window.spotlight){
var x=new Array()
var direction=new Array()
var y=new Array()
if (spotlight.length==null){
spotlight[0]=document.all.spotlight
x[0]=0
direction[0]="right"
y[0]=spotlight[0].height
spotlight[0].filters.light.addPoint(100,50,100,255,255,255,90)
}
else
for (i=0;i<spotlight.length;i++){
x[i]=0
direction[i]="right"
y[i]=spotlight[i].height
spotlight[i].filters.light.addPoint(100,50,100,255,255,255,90)
}
}

function slidelight(cur){
spotlight[cur].filters.light.MoveLight(0,x[cur],y[cur],200,-1)

if (x[cur]<spotlight[cur].width+200&&direction[cur]=="right")
x[cur]+=10
else if (x[cur]>spotlight[cur].width+200){
direction[cur]="left"
x[cur]-=10
}
else if (x[cur]>-200&&x[cur]<-185){
direction[cur]="right"
x[cur]+=10
}
else{
x[cur]-=10
direction[cur]="left"
}
}

if (document.all&&window.spotlight){
if (spotlight.length==null)
setInterval("slidelight(0)",spotlight[0].speed)
else
for (t=0;t<spotlight.length;t++){
var temp='setInterval("slidelight('+t+')",'+spotlight[t].speed+')'
eval(temp)
}
}
</script>