Patent ID: 7319464

Claim:
A method of adjusting a frequency of a dot clock signal for a video signal, said method comprising: (a) generating a first dot clock signal based on a horizontal synchronizing signal of said video signal and a first factor, the first factor representing a ratio of a frequency of the first dot clock signal to a frequency of the horizontal synchronizing signal; (b) sampling said video signal by said first dot clock signal to obtain image data; (c) obtaining a number of beats over one line of said image data using a high pass filtering process, the beats being a low frequency component of the image data over the one line of the image data wherein the frequency of the beats is determined by a difference between a desirable frequency and the actual frequency of the first dot clock signal; (d) correcting said first factor with said number of beats, thereby obtaining a second factor; and (e) generating a second dot clock signal based on said horizontal synchronizing signal and said second factor.