| 摘要 |
PURPOSE:To draw the contents of an area setting memory by software and executing masking in accordance with the contents by reading out the contents of the area setting memory and a video memory synchronously with a picture element address. CONSTITUTION:An area specifying circuit is provided with an A/D converting circuit 2 converting an input video signal into a digital signal, a video memory 11 writing and reading the converted digital signal and the area setting memory 22 masking the signal to be read out. The same picture element size as that of the memory 11 is provided to the memory 22 and an address for reading out the contents of both the memories 11, 22 synchronously is generated from a picture address generating circuit 16 connected to a CPU. A write/read address is generated from an external address setting circuit 23 and addresses from the circuits 16, 23 are switched by address switching circuits 12, 21. The area of a signal written/read out in/from the memory 11 is specified in accordance with the optionally set contents of the memory 22 to attain masking. |
