Television receiver with perceived contrast reduction in a predetermined area of a picture where text is superimposed

摘要

The television receiver includes a text generation mechanism which is capable of superimposing text on a received picture. In order to make the text more legible, while still retaining picture information a reduced contrast area is formed around the text. In order to superimpose the text on the picture text, RGB signals are applied to the video output circuits together with a switching signal (VDS) which causes either text or picture signals to be applied to the display device. To provide a reduced contrast area around the text display the switching signal (VDS) is arranged to switch between the picture signal and blanking level at a fast rate, for example at the clock rate, to produce the reduced contrast area.