Noise Removal from Chrominance Components of a Color Television Signal

A solution to the problem of removing noise from the chrominance components of a color television signal is described. The inherent trade-off between noise removal and signal blurring is balanced adaptively using the luminance signal as a control for changing the characteristics of the chrominance filters. This adaptation is effective because: (1) in real pictures, most sharp changes of color are accompanied by sharp changes in luminance and, (2) sharp changes of luminance have a pronounced masking effect on the chrominance noise. Computer simulations show that a large amount of noise could be removed from the chrominance signals with no appreciable visible blurring. A simple filter, whose performance is close to the optimum, is proposed and a comparison with nonadaptive filters is made.