摘要 |
The present invention provides a technique for appropriately adjusting a dot clock for video signals by a simple process. A process of adjusting a phase of the dot clock first obtains two image data by two dot clocks having different phases, carries out a certain operation for the two image data to calculate a phase-related index representing the relative phase of the dot clock to a video signal with respect to the two image data, and determines a delay that gives a desirable phase to the dot clock based on these phase-related indexes. A first process of adjusting the frequency of the dot clock first obtains image data by a dot clock that has been generated with a provisional factor, calculates a length of an effective signal area on one line of the image data, and determines a desirable factor based on the ratio of a known length to the measured length of the effective signal area. A second process of adjusting the frequency of the dot dock extracts a beat component included in the sampled image data to determine the difference between a provisional factor and a desirable factor.
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