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.