| abstract |
A picture overlay system assures proper image aspect ratios for picture overlays. The system comprises a video memory (350, 356, 358) and a control unit (300) for writing and reading information from a video signal into and out of the video memory, the information relating to video data. A reading circuit (680) supplies information from the video memory synchronously with a display for another video signal. An interpolar (337) selectively compresses and expands the information read from the reading circuit, independently of any other processing which might vertically compress or expand said video data. A multiplexer (312) combines the video signals for simultaneous display. The reading circuit can comprise an asynchronous line memory for the information read from the video memory, having a write port operable synchronously with the reading of the video memory and a read port operable synchronously with the display of the other video signal. |