| 摘要 |
An image displayed on a video monitor screen is surrounded with a uniform dark background. A multiplexer (MUX) has its output coupled to the monitor and one input coupled to a display controller memory for digitized image pixels and another input coupled to a switching circuit for simulating pixel bits which can be all zeros to produce black or dark pixels in the display. For each horizontal scan line the MUX is caused to select the black pixels until the image boundary is reached, then select image pixels until the opposite image boundary is reached and the black pixels are selected again to the end of the line.
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