Display GridView Selected Row Image in Image Control in ASP.Net

You will have to first copy image from the folder into some local directory in ASP.Net, say TempImages and then assign to image control

HTML

<asp:GridView ID = "GridView1" runat="server"  AutoGenerateSelectButton = "true" OnSelectedIndexChanged = "OnSelectedIndexChanged">
</asp:GridView>
<br />  
<asp:Image ID="Image1" runat="server" />

Code

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!this.IsPostBack)
        {
            System.Data.DataTable dt = new System.Data.DataTable();
            dt.Columns.Add("FileName");
            string[] files = System.IO.Directory.GetFiles(@"C:\Users\Public\Pictures\Sample Pictures");
            foreach (string file in files)
            {
                dt.Rows.Add(file);
            }
            GridView1.DataSource = dt;
            GridView1.DataBind();
        }
    }
    protected void OnSelectedIndexChanged(object sender, EventArgs e)
    {
        string filePath  = GridView1.Rows[GridView1.SelectedIndex].Cells[1].Text;
        string newPath = "~/TempImages/" + System.IO.Path.GetFileName(filePath);
        System.IO.File.Copy(filePath, Server.MapPath(newPath), true);
        Image1.ImageUrl = newPath;
    }