<script runat="server">
Sub getCoordinates(sender As Object, e As ImageClickEventArgs)
mess.Text="Coordinates: " & e.x & ", " & e.y
End Sub
</script>
<html>
<body>
<form runat="server">
<p>Click on the image:</p>
<asp:ImageButton
runat="server"
ImageUrl="smiley.gif"
OnClick="getCoordinates"/>
<p><asp:label id="mess" runat="server"/></p>
</form>
</body>
</html>