On the choice of filter orders in subband coding

Summary form only given. The use of subband image coding for intrafield coding (compression) of high-definition television (HDTV) signals has been studied. Filter banks with low-order filters that have simple coefficients are attractive for these applications due to the ease in implementation. The results of a limited study to evaluate the impact of the choice of filter orders in HDTV coding are discussed. The study shows that the interplay between the filters and the quantization either in the sample or in the transform domain is very critical in determining the quality of the reconstructed picture. Subband signals that are generated by a four-band subband decomposition using exact reconstruction infinite-impulse-response (IIR) filter banks were considered. A comparison of the quality of reconstruction with approximately linear-phase IIR filters of different orders was made. The work showed that for signals with large high-frequency content the use of low-order filters in the filter bank provides less noticeable degradation compared with that in the case of higher-order filter banks when the same quantization parameters are used.<>