COMPUTER, OVERLAY PROCESSOR, AND OVERLAY PROCESS IMPLEMENTING METHOD

摘要

PROBLEM TO BE SOLVED: To sharply display a moving picture on a hold type display device by providing a shutter function in the overlay processor. SOLUTION: A RAM readout circuit 301 reads image data and moving picture data out of an on-screen area 211 and an off-screen area 213 according to horizontal scanning lines, and outputs them to a key color detecting circuit 303 and an overlay selecting circuit 305. A shutter circuit 307 receives a frame timing signal from a VRAM readout circuit 301 and judges which of a black signal and the moving picture data received from the VRAM readout part 301 should be outputted in a frame according to specific frame cycles. In the starting frame cycle, the moving picture data from the VRAM readout circuit 301 are outputted to the overlay selecting circuit 305, so the black signal is outputted to the overlay selecting circuit 5 after a next framing signal is received.