Patent ID: 6924796

Claim:
A method of adjusting a dot clock in an image display apparatus, comprising the steps of: (a) sampling an image signal in synchronization with the dot clock, the dot clock having a certain frequency and phase; (b) calculating a first image characteristic by calculating differences between consecutively sampled values over a certain interval in the image signal and obtaining an extremum value from the calculated differences over the certain interval, the extremum value being specified as the first image characteristic; (c) repeating said steps (a) and (b) while varying the phase of the dot clock, thereby measuring the first image characteristic over a range of phase values; (d) deciding, from results obtained in step (c), whether the frequency of the dot clock is correct; and (e) changing the frequency of the dot clock and repeating said steps (a) to (d), if the frequency of the dot clock is incorrect.