Try this javaScript to change image background on page refresh/page reload...........
<script type="text/javascript">
function banner() { } ; b = new banner() ; n = 0
b[n++]= "<img name=randimg src='icon/p1.jpg' width=100% height=395>"
b[n++]= "<img name=randimg src='icon/p2.jpg' width=100% height=395>"
b[n++]= "<img name=randimg src='icon/p3.jpg' width=100% height=395>"
i=Math.floor(Math.random() * n) ;
document.write( b[i] )
</script>
<script type="text/javascript">
function banner() { } ; b = new banner() ; n = 0
b[n++]= "<img name=randimg src='icon/p1.jpg' width=100% height=395>"
b[n++]= "<img name=randimg src='icon/p2.jpg' width=100% height=395>"
b[n++]= "<img name=randimg src='icon/p3.jpg' width=100% height=395>"
i=Math.floor(Math.random() * n) ;
document.write( b[i] )
</script>