OPTIMIZATION OF WEIGHTED SIGNAL-TO-NOISE RATIO FOR A DIGITAL VIDEO ENCODER

摘要

When processing video television information the low frequency band is inherently of primary interest due to the natural averaging properties of the human eye, combined with the limited frequency response of video display elements such as phosphorus and liquid crystal displays. Noise is generated and observed in the low frequency region of digitized analog video signals due to nonlinearities inherent in the digitization process. This invention reduces the noise measured in the low frequency region by shifting the noise upband and out of the frequencies of interest by adding a dither signal to the analog input signal and employing a 2X decimation digital filter to remove the unwanted dither and spurious intermodulation signals. The disclosed invention allows for a simple and inexpensive means for removal of the dither signal without having to resort to complex dither subtraction techniques employed in the prior art.