You can use the OverlayCommand to create a watermark using ApplyCommand in either the WorkspaceViewer, WebImageViewer, or Workspace objects.
AtalaImage myOverlay = new AtalaImage("c:\\myLogo.png");
WebImageViewer1.ApplyCommand(new OverlayCommand(myOverlay, new Point(10, 10)));
The image being overlayed can contain alpha transparency which will be alpha blended onto the bottom image.
Alternatively, if you need to overlay text onto an image, you can use the Canvas object to draw directly onto a 1-bit, grayscale, or RGB image or you can use .NET's GDI+ routines to draw a string onto an image.
Watermarking was demonstrated during our 31 apps in 31 days promotion. Here is a link: