Signal/noise performance evaluation for colour-television picture sources

The signal/noise performance of a colour picture source is known to be an extremely difficult parameter to measure and specify. Owing to the complexity of signal processing within the picture chain, conventional methods of measuring r.m.s. noise levels at the outputs of the picture source can give a figure of merit that is substantially different from that obtained by direct observation of the subjective noise impairment of the final displayed picture. The paper describes the results of research to establish standard test procedures for the measurement of noise in picture sources. It is shown that noise-measuring equipment may be designed that yields a figure of merit termed `the display signal/noise ratio¿ for the source under test. This figure of merit corresponds well with the subjective noise performance of the equipment.