Dynamically set Image Url at runtime for Image Control inside GridView in ASP.Net

my requirement was i have to display image in one of the gridview column with text at runtime. since there is no image column in database table, also no need to save that image in database, just to display in gridview at run time.

HTML code:

<asp:GridView ID="GridView3" runat="server" AllowPaging="True"  DataKeyNames="DangerDownstream"
               onpageindexchanging="GridView3_PageIndexChanging" backcolor="White"
               onrowdatabound="GridView3_RowDataBound" PageSize="5" Width="100%" 
               AutoGenerateColumns="False" EnableModelValidation="True">
               <RowStyle CssClass="station_grid" />              
               <Columns>
                   <asp:BoundField DataField="DangerDownstream" />
                     <asp:TemplateField HeaderText="Notification">
                     <ItemTemplate>
                         <asp:Image ID="Img" runat="server" Height="25px" Width="25px" />
                         <asp:Label ID="Ln" runat="server" Text="Label"></asp:Label>
                     </ItemTemplate>
                     </asp:TemplateField>
               </Columns>
               
           </asp:GridView>

C# code:

Label lb = (Label)e.Row.Cells[3].FindControl("Ln"); 
lb.Text = "DANGER level";
System.Web.UI.WebControls.Image img = (System.Web.UI.WebControls.Image)e.Row.Cells[2].FindControl("Img"); 
img.ImageUrl = "~/Images/warning2.png";