This example demonstrates how to change the transparency of a given image using the ImageEditor control. Creating an ImageEditorTool with command name Opacity will render a tool on the RadImageEditor's ToolBar that will enable you to modify the picture using the built-in Opacity dialog.
It is, however, not necessary for this tool to be present, for the user to be able to set opacity on her image. The RadImageEditor's changeImageOpacity(opacity) client-side method can be used for this purpose, where the opacity parameter is an integer between 0-100 (percents).
RadImageEditor sets the transparency directly on the client, so the changes are not actually applied to the image until a postback occurs.