C#: how can I add image watermark at left bottom of a directory's pictures?

FileStream

C#
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
using System.IO;
using System.Drawing.Imaging;
 
namespace WatermarkImages
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            this.folderBrowserDialog1.Description =
            "Select the images directory";
 
            // Disallow creation of new files using the FolderBrowserDialog.
            this.folderBrowserDialog1.ShowNewFolderButton = false;
        }
 
       
        private void btnWatermark_Click(object sender, EventArgs e)
        {
            string path = String.Empty;
            DialogResult result = folderBrowserDialog1.ShowDialog();
            if (result == DialogResult.OK)
            {
                path = folderBrowserDialog1.SelectedPath;
            }
 
            if (path == String.Empty)
            {
                lblStatus.Text = "Invalid directory..";
                return;
            }
 
 
            lblStatus.Text = String.Empty;                       
            Image img = null;
            string fullPath = String.Empty;
           
            try
            {
                string[] imgExtension = { "*.jpg", "*.jpeg", ".gif", "*.bmp" };
                List<FileInfo> files = new List<FileInfo>();               
               
                DirectoryInfo dir = new DirectoryInfo(path);
               
                foreach (string ext in imgExtension)
                {
                    FileInfo[] folder = dir.GetFiles(ext, SearchOption.AllDirectories);
                    foreach (FileInfo file in folder)
                    {
                        FileStream fs = file.OpenRead();
                        fullPath = path + @"\" + file.Name ;
           
                        Stream outputStream = new MemoryStream();
                        AddWatermark(fs, "www.dotnetcurry.com", outputStream);
                        fs.Close();
                        file.Delete();
                        img = Image.FromStream(outputStream);
 
                        using (Bitmap savingImage = new Bitmap(img.Width, img.Height, img.PixelFormat))
                        {
                            using (Graphics g = Graphics.FromImage(savingImage))
                                g.DrawImage(img, new Point(0, 0));
                            savingImage.Save(fullPath, ImageFormat.Jpeg);            
                           
                        }
                      
                        img.Dispose();
                       
                    }
                }
                lblStatus.Text = "Processing Completed";
            }
            catch (Exception ex)
           {
               lblStatus.Text = "There was an error during processing..";           
            }
            finally
            {
                if (img != null)
                    img.Dispose();
            }
      }
 
 
        public void AddWatermark(FileStream fs, string watermarkText, Stream outputStream)
        {
            Image img = Image.FromStream(fs);               
            Font font = new Font("Verdana", 16, FontStyle.Bold, GraphicsUnit.Pixel);
            //Adds a transparent watermark with an 100 alpha value.
            Color color = Color.FromArgb(100, 0, 0, 0);
            //The position where to draw the watermark on the image
            Point pt = new Point(10, 30);
            SolidBrush sbrush = new SolidBrush(color);
 
            Graphics gr = null;
            try
            {
                gr = Graphics.FromImage(img);
            }
            catch
            {
                // http://support.microsoft.com/Default.aspx?id=814675
                Image img1 = img;
                img = new Bitmap(img.Width, img.Height);
                gr = Graphics.FromImage(img);
                gr.DrawImage(img1, new Rectangle(0, 0, img.Width, img.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel);
                img1.Dispose();
            }
                       
            gr.DrawString(watermarkText, font, sbrush, pt);
            gr.Dispose();
           
            img.Save(outputStream, ImageFormat.Jpeg);
        }
    
    }
}