Display default image (NotFound) when image does not exist in ASP.Net GridView

  <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" OnRowDataBound = "OnRowDataBound">
        <Columns>
            <asp:TemplateField HeaderText = "Images">
                <ItemTemplate>
                    <asp:Image ID="Image1" runat="server" Height = "100" Width = "100" ImageUrl = '<%# Eval("FilePath") %>' />
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Configuration;
using System.Data.SqlClient;
using System.Data;
using System.IO;

public partial class CS : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            GridView1.DataSource = GetData();
            GridView1.DataBind();
        }
    }

    private DataSet GetData()
    {
        string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        string query = "SELECT * FROM Images";
        SqlCommand cmd = new SqlCommand(query);
        using (SqlConnection con = new SqlConnection(conString))
        {
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;

                sda.SelectCommand = cmd;
                using (DataSet ds = new DataSet())
                {
                    sda.Fill(ds);
                    return ds;
                }
            }
        }
    }

    protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            Image image = e.Row.FindControl("Image1") as Image;
            if (!File.Exists(Server.MapPath(image.ImageUrl)))
            {
                image.ImageUrl = "images/NotFound.png";
            }
        }
    }
}