In this correspondence, we present an algorithm for restoration of star field images by incorporating both the minimum mean square error and the maximum varimax criteria. It is assumed that the point spread function of the distortion system can be well approximated by a Gaussian function. Simulated annealing (SA) is used to implement the optimization procedure. Simulation results for both Gaussian and square point spread functions with heavy additive independent white Gaussian noise are provided. Visual evaluation of the results indicate that the proposed algorithm performs better than the noncausal Wiener filtering method.

The transmission of NTSC composite color images over digital communication channels is generally accomplished by coding the less correlated component signal, YIQ. Unless the video source is available, the component signals are separated from the composite signal by using comb-filters. Comb-filtering is generally performed in the temporal domain. This paper shows that by properly sampling the NTSC composite color signal at four times the color subcarrier, the Walsh-Hadamard transform acts like a comb filter and separates the YIQ components of the composite signal. The YIQ components will be mapped into specific locations of the coefficient matrix.

Predictors operating on video signals sampled at six times the color subcarrier(6f_{c})have been investigated and compared with predictors operating at three times the color subcarrier(3f_{c}). When the best6f_{c}predictor is used with an adaptive delta modulator (ADM) step size generator, the resulting pictures are similar in quality to3f_{c}predictors operating with a four-level adaptive DPCM quantizer. An ADM coder was implemented in real time. The coder used between 24 and 34 IC's, depending upon the algorithm, and fits on a single 9 in × 6 in PC board. The transmission rate is 21.4 Mbits/s.

This paper describes a one-stage look-ahead algorithm for adaptive delta modulators. The algorithm does not require the calculation of two encoding paths nor does it require the decision circuitry to choose the optimum path.

This paper presents the results of a study in data compression of adaptive delta modulated video signals. The Song mode ADM is first investigated at a sampling rate of 16 Mbits/s and shown not to produce enough redundancy to warrant entropy encoding. We then present a modified adaptive delta modulator algorithm that operates at a sampling rate of 16 Mbits/s and does produce sufficient redundancy to yield a 40-50 percent data compression by using a simple code on 4 bit data blocks. Other techniques such as field interpolation and direct substitution are shown to increase the possible data compression further without noticeable degradation in the two input images used in this investigation. The effects of channel errors in the transmission of packet video over a computer network are considered. A leaky integrator is used to reduce the effects of channel errors in the data bits. We show that the effects of channel errors can be reduced by field interpolating those packets that can be shown to contain errors.