When you upload images to your website, you might want to add a watermark to the image
before you save it or display it on a page. People often use watermarks to add copyright
information to an image or to advertise their business name. RichTextEditor has
the built-in function which allows you watermark images when uploading using ASP.NET code.
This example also shows how to use Editor.UploadImage Event to execute custom actions when an image is uploaded successfully.
Watermark Text :