NHK has been producing a number of HD programs, such as operas performances and the artical plays from around the world. For these programs, a lot of captions are needed as they are in foreign languages. This system has the ability to generate HDTV font images in real-time and superimpose them on the original HDTV programs simultaneously. The development of this system provides us with an opportunity to produce more programs in highter quality and also to work more efficiently with our time.