| 摘要 |
A digital keystone modulation circuit for transforming a digital image to a digital projection image is disclosed. The digital image and the digital projection image have n horizontal image signals and n horizontal projection image signal respectively. The digital keystone modulation circuit includes an output controller for outputting a (3k-1)th image signal and one of a (3k-2)th and (3k)th image signal in response to an output image selected signal, an output image selector for outputting a first counting signal and the output image selected signal in response to a localization sync-signal, a first counting controller for counting in response to the counting signal, a kth horizontal projection image frequency, and a dot number of one of the (3k-2)th and (3k-1)th image signal, a second counting controller for counting in response to the output image selected signal, the kth horizontal projection signal, and a dot number of the (3k-1)th image signal, and a projection image frequency generator for outputting the kth projection image frequency in response to a horizontal sync-signal and a sum of the dot numbers of the (3k-2)th, (3k-1)th, and (3k-1)th image signals.
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