Invisible watermark using VB.NET

I've a project where users can upload images onto the server and i have to add an invisible water mark into it. anyway,i've recommended that it would be better to purchase or use a 3rd party API that allows the invisible watermarking to be done using VB.NET. So i was wondering does anyone have any recommendations

Re: Invisible watermark using VB.NET

With this function you can draw some text on an image, so that its easy to retrieve the position of text

Imports System.Drawing.Imaging
Imports System.Drawing
  
Private Sub TextOnImage(ByVal OldImage As String, ByVal NewImage As String, ByVal Text As String, ByVal Format As ImageFormat, ByVal Font As Font, ByVal Color As Color, ByVal Position As Point)
  Dim TmpSize As System.Drawing.Size
  Dim Image As Image = System.Drawing.Image.FromFile(OldImage)
  Dim Brush As New SolidBrush(Color)
  
  'Read Image Dimensions
  TmpSize.Height = Image.Height
  TmpSize.Width = Image.Width
  
  'Create a new Bitmap Object
  Dim NewBitmap As New System.Drawing.Bitmap(Image, TmpSize)
  
  'Create a new Graphic Object
  Dim Graphic As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(NewBitmap)
  
  'Draw String on Image
  Graphic.DrawString(Text, Font, Brush, Position)
  
  'Save new Image
  NewBitmap.Save(NewImage, Format)
  
  Graphic.Dispose()
  NewBitmap.Dispose()
End Sub