| 摘要 |
The aspect ratio of a television system is increased by reducing the number of active lines in the vertical direction and using those lines to insert information for increasing the width of horizontal lines. The added information is superimposed at or near black level so that conventional receivers will merely see a shorter image without the increased width. To minimize the visibility of the added information, the high-energy low frequencies can be reduced. Alternatively the low frequency information for lengthening the horizontal lines can be placed in compressed form on either side of the normal horizontal lines without being seen on conventional receivers or used to modulate a high-frequency burst placed in the inactive lines. The increased aspect ratio receiver decodes the information in the inactive vertical lines, adds it to the decoded low frequency information, and displays it as an increased aspect ratio image in HDTV receivers. The decrease in vertical height and increase in horizontal width can provide approximately a 5/3 aspect ratio with significantly altering the height of the image on conventional receivers.
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