PURPOSE: To improve the utilization efficiency of a memory and prevent the disturbance of a display image by writing both the overlay image data and window ID data on one memory.
CONSTITUTION: The window ID data are written at the window position in an overlay/window ID plane memory 21, and the basic data of an overlay image are written at the position other than the window. A comparing circuit 10 compares the data read out from the memory 21 and the data inputted from an ID generating circuit 12. The circuit 10 generates a coincidence output only when the window ID data of the written subject are read out. The inputted image data on only the picture elements fed with the coincidence output from the circuit 10 are written into RGB plane memories 5, 6. The window image data can be written into the preset window.
IMAI MASATOSHI
HIRASE HIDEHIRO
TAKASHIMA SHINJI
