Faramarz Azadegan

Introduction of an NTSC compatible HDTV system-HDS/NA

The HDS/NA (High-Definition System for North America) contribution to the process of defining a compatible ATV (advanced TV) system is described. The following advantages of the HDS/NA approach are noted: compatibility on an even-handed basis among the three modes of television delivery-satellite, CATV, and terrestrial broadcast; a linear subsampling technique that offers an effective bandwidth reduction and simple receiver implementation; FM-friendly satellite feeder and/or DBS (direct broadcast service) delivery system; low-power transmission of the HDNTSC (high-definition National Television System Committee) augmentation channel, which should allow the use of the taboo channel without interfering with other TV channels using the same frequency band. >

Discrete cosine transform encoding of two-dimensional processes

The performance of a two-dimensional (2D) block discrete cosine transform (DCT) operating on 2D first-order separable autoregressive Gauss-Markov processes and real-world images is studied. In each case, Lloyd-Max and entropy-constrained quantizers with optimum rate-allocation are employed. These results are compared to the earlier developments for vector predictive quantizers and entropy-constrained 2-D differential pulse code modulation (DPCM). Relative performance improvements that can be obtained for the schemes under consideration, when operating on the same source (either stochastic or select real-world images), are established. The results obtained for real-world images indicate the degree to which the theoretical results can be extended to practical applications.<<ETX>>