An on-screen display system is adapted for displaying OSD information on an OSD background portion which is selectively filled with either an half tone video image or a background raster of a specific color selected by a user, or which is filled by superimposing the half tone video image and the half tone background raster selected by the user. Mixing and amplifying circuits are provided for each of three red/green/blue (R/G/B) channels. Each of the three mixing and amplifying circuits receives a video signal and an OSD signal of a respective channel, mixes the video signal and the OSD signal according to a video selection signal and an OSD selection signal, amplifies a mixed signal, and outputs an amplified image signal to a display. A selection signal generating circuit receives OSD signals for R/G/B channels, a video/OSD switching signal, a half tone signal, and OSD control signals generates and outputs the OSD selection signal and the video selection signal. When the video/OSD switching signal instructs an OSD output operation and the half tone signal instructs a half tone output operation, the selection signal generating circuit outputs the video selection signal and the OSD selection signal such that a half tone OSD background raster is displayed with a half tone video image in a predetermined OSD window.