Hi smile,

Refer the below article i have created the example.

Dynamically Generate and Display Barcode Image in ASP.Net

Check this example. Now please take its reference and correct your code.

HTML

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" AutoGenerateSelectButton="true"
    OnSelectedIndexChanged="GridView1_SelectedIndexChanged">
    <Columns>
        <asp:BoundField DataField="Id" HeaderText="Id" />
        <asp:BoundField DataField="Name" HeaderText="Name" />
        <asp:BoundField DataField="Country" HeaderText="Country" />
        <asp:TemplateField>
            <ItemTemplate>
                <asp:HiddenField runat="server" ID="hfBarcode" Value='<%# Eval("Barcode") %>' />
                <asp:Image ID="imgBarcode" runat="server" />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

Namespaces

C#

using System.Drawing;
using System.IO;
using System.Data;

VB.Net

Imports System.Drawing
Imports System.IO
Imports System.Data

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[4] { new DataColumn("Id", typeof(int)),
                        new DataColumn("Name", typeof(string)),
                        new DataColumn("Country",typeof(string)),
                        new DataColumn("Barcode") });
        dt.Rows.Add(1, "John Hammond", "United States", "1241972");
        dt.Rows.Add(2, "Mudassar Khan", "India", "7208922");
        dt.Rows.Add(3, "Suzanne Mathews", "France", "2387841");
        dt.Rows.Add(4, "Robert Schidner", "Russia", "1254577");
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
}

protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
    GridViewRow row = (sender as GridView).SelectedRow as GridViewRow;
    string barCode = (row.FindControl("hfBarcode") as HiddenField).Value;
    System.Web.UI.WebControls.Image imgBarCode = row.FindControl("imgBarcode") as System.Web.UI.WebControls.Image;
    using (Bitmap bitMap = new Bitmap(barCode.Length * 20, 40))
    {
        using (Graphics graphics = Graphics.FromImage(bitMap))
        {
            Font oFont = new Font("IDAutomationHC39M", 16);
            PointF point = new PointF(2f, 2f);
            SolidBrush blackBrush = new SolidBrush(Color.Black);
            SolidBrush whiteBrush = new SolidBrush(Color.White);
            graphics.FillRectangle(whiteBrush, 0, 0, bitMap.Width, bitMap.Height);
            graphics.DrawString("*" + barCode + "*", oFont, blackBrush, point);
        }
        using (MemoryStream ms = new MemoryStream())
        {
            bitMap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
            byte[] byteImage = ms.ToArray();

            Convert.ToBase64String(byteImage);
            imgBarCode.ImageUrl = "data:image/png;base64," + Convert.ToBase64String(byteImage);
        }
    }
}

VB.Net

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim dt As New DataTable()
        dt.Columns.AddRange(New DataColumn() {New DataColumn("Id", GetType(Integer)), _
                                                New DataColumn("Name", GetType(String)), _
                                                New DataColumn("Country", GetType(String)), _
                                                New DataColumn("Barcode", GetType(String))})
        dt.Rows.Add(1, "John Hammond", "United States", "1241972")
        dt.Rows.Add(2, "Mudassar Khan", "India", "7208922")
        dt.Rows.Add(3, "Suzanne Mathews", "France", "2387841")
        dt.Rows.Add(4, "Robert Schidner", "Russia", "1254577")
        GridView1.DataSource = dt
        GridView1.DataBind()
    End If
End Sub

Protected Sub GridView1_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles GridView1.SelectedIndexChanged
    Dim row As GridViewRow = TryCast((TryCast(sender, GridView)).SelectedRow, GridViewRow)
    Dim barCode As String = TryCast(row.FindControl("hfBarcode"), HiddenField).Value
    Dim imgBarCode As System.Web.UI.WebControls.Image = TryCast(row.FindControl("imgBarcode"), System.Web.UI.WebControls.Image)
    Using bitMap As New Bitmap(barCode.Length * 20, 40)
        Using graphics__1 As Graphics = Graphics.FromImage(bitMap)
            Dim oFont As New Font("IDAutomationHC39M", 16)
            Dim point As New PointF(2.0F, 2.0F)
            Dim blackBrush As New SolidBrush(Color.Black)
            Dim whiteBrush As New SolidBrush(Color.White)
            graphics__1.FillRectangle(whiteBrush, 0, 0, bitMap.Width, bitMap.Height)
            graphics__1.DrawString("*" & barCode & "*", oFont, blackBrush, point)
        End Using
        Using ms As New MemoryStream()
            bitMap.Save(ms, System.Drawing.Imaging.ImageFormat.Png)
            Dim byteImage As Byte() = ms.ToArray()
            Convert.ToBase64String(byteImage)
            imgBarCode.ImageUrl = "data:image/png;base64," & Convert.ToBase64String(byteImage)
        End Using
    End Using
End Sub

Screenshot