| 摘要 |
A video signal processor includes a sharpening circuit, a non-correlation detecting circuit, and, optionally, a noise level detecting circuit. The sharpening circuit is capable of receiving an input luminance signal. The sharpening circuit has a transversal filter. The transversal filter is operable to filter the input luminance signal to produce an intermediate signal and to produce a filtered luminance signal with a time lag. The sharpening circuit is operable to multiply the filtered luminance signal by a predetermined factor, to adjust the time lag to produce a resultant luminance signal, and to add the resultant luminance signal to the intermediate signal. The non-correlation detecting circuit detects noise or fluctuation in the intermediate signal. The non-correlation detecting circuit is operable to set the predetermined factor to a selected value based upon the presence of at least one of the noise or the fluctuation in the intermediate signal, according to a threshold voltage. The noise level detecting circuit detects a noise level. The threshold voltage is varied depending upon the noise level. When the intermediate signal is detected to contain the noise but not the fluctuation, the sharpening circuit cancels at least a portion of the noise. Thus, the video signal processor discriminates a low-level signal from a large-amplitude noise, and reduces noise contained in a video signal.
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