A method for generating a plurality of on-screen display (OSD) data is used in a back-end (BE) circuit. The BE circuit is configured to process a plurality of image data to be displayed on a display device. The method includes steps of: receiving the plurality of image data from an application processor (AP); and extracting information of a detecting layer embedded in the plurality of image data, wherein the information of the detecting layer indicates the plurality of OSD data corresponding to at least one user-interface (UI) layer in the plurality of image data.