Visible an Image while uploding a file from fileupload

javascript code

  <script type="text/javascript" src="http://code.jquery.com/jquery-1.8.2.js"></script>
      <script type="text/javascript">
        function showimagepreview(input) {
            if (input.files && input.files[0]) {
                var filerdr = new FileReader();
                filerdr.onload = function (e) {
                    $('#img1').css("visibility", "visible");
                }
                filerdr.readAsDataURL(input.files[0]);
            }
        }
    </script>

.aspx

 <asp:Image ID="img1" runat="server" ImageUrl="~/b1.png" style="visibility:hidden"/>
        <asp:FileUpload ID="FileUpload1" runat="server" onchange="showimagepreview(this)"/>