| 摘要 |
A method for detecting a synchronous signal contained in an input image signal is provided. In the method, horizontal and vertical periods are established during which horizontal and vertical synchronous signal pulses contained in the input image signal are counted, respectively. Then, minimum and maximum horizontal values which correspond to the horizontal synchronous signal pulses contained in the horizontal period are established, and minimum and maximum vertical values which correspond the vertical synchronous signal pulses contained in the vertical period are established. Afterwards, the horizontal and vertical synchronous signal pulses are counted during the horizontal and vertical periods to respectively obtain first and second counted values. Then, the method determines if the first counted value is greater than or equal to the minimum horizontal value and less than or equal to the maximum horizontal value and determines if the second counted value is greater than or equal to the minimum vertical value and less than or equal to the maximum vertical value. Subsequently, the method determines than an actual synchronous signal is contained in the input image signal if the first counted value is greater than or equal to the minimum horizontal value and less than or equal to the maximum horizontal value and the second counted value is greater than or equal to the minimum vertical value and less than or equal to the maximum vertical value.
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