How to reduce the size of an image using c sharp

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C#

Dear All,


I want to reduce the picture size less than 50 kb. Here i am giving the code which i have used in my application.

byte[] imageSize = new byte[FileUpload1.PostedFile.ContentLength];
HttpPostedFile uploadedImage = FileUpload1.PostedFile;
uploadedImage.InputStream.Read(imageSize(int)FileUpload1.PostedFile.ContentLength);
var fileLength1 = (FileUpload1.FileContent.Length.ToString());
byte[] ImageData = GenerateThumbnails(0.005, uploadedImage.InputStream);
private byte[] GenerateThumbnails(double scaleFactor, Stream sourcePath)
{
      var image = System.Drawing.Image.FromStream(sourcePath);
      var newWidth = (int)(image.Width * scaleFactor);
      var newHeight = (int)(image.Height * scaleFactor);
      var thumbnailImg = new Bitmap(newWidth, newHeight);
      var thumbGraph = Graphics.FromImage(thumbnailImg);
      thumbGraph.CompositingQuality = CompositingQuality.HighQuality;
      thumbGraph.SmoothingMode = SmoothingMode.HighQuality;
      thumbGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;
      var imageRectangle = new Rectangle(0, 0, newWidth, newHeight);
      thumbGraph.DrawImage(image, imageRectangle);

      MemoryStream ms = new MemoryStream();
      image.Save(ms, ImageFormat.Jpeg);
      return ms.ToArray();
}

Here,the fumction GenerateThumbnails reduce the actual size of the picture but it is very low.Suppose i upload the image which has 800 kb ,function will reduce only 40 kb from 800 kb.Size of the image affectiong the perfomance of my website.So if anyone know the answer please help me.

Thanks in advance.

Regards,
Rajeev K.