Automatic assessment of signal-to-thermal noise ratio of television images

A novel method which measures the thermal noise content in any television picture is presented. Our method has the following advantages (1) it is non-intrusive and does not require the use of a test signal, (2) the noise assessment is carried in the spatial domain and not in the frequency domain, thus the use of the expensive spectrum analyzer instrument is not required. The other proposed non-intrusive and spatial domain methods are limited in their accuracy up to around 40 dB signal-to-noise ratios. Above that the resulting accuracies are unacceptable. Our method yields accurate results up to 48 dB. The new FCC regulations require the operating signals-to-noise ratios to be at least equal to 40 dB. Prior to estimating the noise our method applies a filter on the picture. This filter suppresses the originally intended (non-noisy) contents of the picture but retains enough information about the noise present. From this information, an estimate of the noise present is calculated