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IEEE International Symposium on Intelligent Control (ISIC)

作者： M. Herman K. Chaconas M. Nashman T.-H. Hong Sensory Intelligence Group Robot Systems Division National Bureau of Standards Gaithersburg MD USA

Several algorithms that have been implemented as possible candidates for a hybrid video compression system to be used for remote driving of a ground vehicle are described. The algorithms have been implemented on the pipelined image processing engine (PIPE) real-time image processing machine. The PIPE has been integrated with a remote control vehicle system, and the algorithms were evaluated by means of real-world remote driving experiments. These experiments have shown that remote vehicle driving is difficult enough without degrading the imagery through compression algorithms. The degraded imagery makes driving even more difficult. The following difficulties were found in driving in cross country terrain using either the full video or the compressed video: global relative vehicle location is very difficult for the driver to obtain; the orientation of the local ground surface is very difficult to obtain; ditches, gullies, and other obstacles are difficult to distinguish; and the range of objects from the vehicle is difficult to determine. It appears that performing compression by transmitting images at a rate of, at most, a few per second and then providing a realistic video simulation to the operator may be one of the most effective ways of performing video compression.< >

关键词： Vehicle driving Video compression Land vehicles Image processing Degradation Image coding Road vehicles Engines Remotely operated vehicles compression algorithms

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String dictionary structure for Markov arithmetic encoding

String dictionary structure for Markov arithmetic encoding

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IEEE International Conference on Communications (ICC)

作者： Y. Bar-Ness S. Choi S. Politi The Center of Communication and Signal Processing Research Department of Electrical Engineering New Jersey Institute of Technology Newark NJ USA

Data from statistically unknown sources is generally difficult to compress with significant ratios. The compression scheme should have the ability to gather context information of the source in an adaptive manner. Arithmetic coding has that capability and can be made to outperform many other compression schemes known. The sliding dictionary, on the other hand, is a compression algorithm which is best suitable for hardware implementation on systolic-array parallel processors, but due to the statistical properties of its information context, it results in inferior compression ratios. A string dictionary structure is proposed that combines the advantages of both algorithms, offering the possibility of hardware implementation on VLSI, avoidance of encoding almost random information, and encoding with arithmetic codes.< >

关键词： Dictionaries Arithmetic Encoding Hardware Very large scale integration Signal processing algorithms Data compression Adaptive signal processing Context compression algorithms

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VLSI IMPLEMENTATION OF A DPCM compression ALGORITHM FOR DIGITAL TV

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IEEE TRANSACTIONS ON COMMUNICATIONS 1987年第8期35卷 854-856页

作者： BRAINARD, RC OTHMER, JH AT&T Bell Lab. Holmdel NJ USA

Future video services in the loop plant may be based on digital transmission through optical fibers. A small and inexpensive codec is required for a variety of services based on digital television. We have demonstrated a compression algorithm for transmission of NTSC color television over a DS3 channel (44.736 Mbits/s). This predictive coding algorithm has been implemented using circuits built with conventional TTL logic. The resulting picture is visually unimpaired, but may not have network quality. The major portion of the compression or reconstruction circuit has also been implemented in one CMOS VLSI chip. compression is accomplished using this chip with two small ROM chips. Reconstruction is done with the same VLSI chip and one ROM chip.

关键词： Very large scale integration compression algorithms Digital TV Circuits Read only memory Video compression Optical fibers Codecs Predictive coding Prediction algorithms

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The effects of controlled speech level input on the intelligibility testing of speech compression algorithms

The effects of controlled speech level input on the intellig...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： J. Sims J. Tardelli ARCON Corporation Waltham MA USA

Speech level measurements were made for a collection of Diagnostic Rhyme Test (DRT) word lists as used for intelligibility testing of voice communications systems. These measurements were used in the generation of a subsequent set of DRT source tapes for which all DRT list segments on the tapes were equalized with respect to speech level. The effects of this equalization on intelligibility scores was evaluated for unprocessed and processed speech (both parametric and waveform coding algorithms). The manipulation of the speech levels for the DRT lists did not result in significant, predictable, and replicable effects on either system mean scores or on the DRT score variability across lists. The absence of effects was noted for all speech processing conditions and for both male and female speakers. Practical advantages in the use of the equalized word lists are discussed.

关键词： compression algorithms System testing Speech processing Materials testing Level measurement Speech coding Speech analysis Audio recording Meter reading Contracts

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A Simple Predictive Transform Coder for Images

A Simple Predictive Transform Coder for Images

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MILCOM, Military Communications Conference

作者： Erlan H. Feria Joseph Barba Norman Scheinberg City College and Graduate Center City University of New York Staten Island NY USA

In this paper a simple predictive transform coder is proposed for the processing of images. The coder is intrafield and predicts the coefficients of a two-dimensional Hadamard transform based on the past pels immediately surrounding the transformed block. The cost and performance of the new coder compares well with that of other techniques. For example, a predictive transform coder acting on 2×2 picture blocks and operating at an average bit rate of 2 bits/pel is found to yield significantly better picture quality than that derived from a 2×2 or even a 4×4 Hadamard coder. Also, just as important, the physical implementation of this coder requires from two to three times the number of on-line operations required by a 2×2 Hadamard coder and 1/4 to 1/3 that of a 4×4 Hadamard coder.

关键词： Error correction Error correction codes Data compression Costs Transform coding Delay Bit rate compression algorithms

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EXTENSIONS TO THE STEP TRANSFORM SAR PROCESSING TECHNIQUE

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 1985年第3期21卷 338-344页

作者： WU, KH VANT, MR Station H. Ottawa Communications Rcscarch Centre ONT Canada

In previous descriptions of the step transform SAR azimuth compression algorithm, it has been assumed that the azimuth signal is linear FM and is strictly confined within a single range cell. These conditions do not always hold. Under stringent imaging conditions range curvature occurs, i.e., a nonlinear range migration of the energy associated with a point target takes place. If the system must also operate at a high squint angle, the azimuth signal becomes nonlinear FM. This paper describes extensions to the basic step transform algorithm that allow these imaging situations to be accommodated.

关键词： Radar antennas Radar imaging Spaceborne radar Doppler radar Azimuth Frequency modulation Synthetic aperture radar Directive antennas Image coding compression algorithms

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A TECHNIQUE FOR HIGH-PERFORMANCE DATA-compression

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COMPUTER 1984年第6期17卷 8-19页

作者： WELCH, TA DIGITAL EQUIPMENT CORP MAYNARDMA 01754 SPERRY RAND CORP RES CTRSUDBURYMA 01776

First Page of the Article

关键词： Data compression Image coding compression algorithms Programming profession Data structures Encoding Runtime System performance

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Composite-Component Transformation and Predictive Coding of the Component Color TV Signal

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IEEE Journal on Selected Areas in Communications 1984年第2期2卷 353-358页

作者： Li, C.E. Rao, K.R. Rockwell International WESCOM Inc. Downer's Grove IL 60515 United States Department of Electrical Engineering University of Texas at Arlington Arlington TX 76019 United States

Component coding of the NTSC color TV signal is investigated. This coding involves digital demodulation of the composite signal sampled at three times the color subcarrier frequency, the implementation of the compression algorithms on the subsampled component signal, and digital reconstruction of the processed NTSC color signal. The comb filter, bandpass filter, and Hilbert transformer are used for the demodulation of the luminance and the I and Q chrominance signals. The reconstructed components at the receiver are interpolated and modulated to obtain the composite signal. Different combinations of comb filters, bandpass filters and Hilbert transformers are used to investigate their effect on composite-component separation and reconstruction. Because of their reduced bandwidths, the chrominance signals are subsampled both horizontally and vertically. Several intrafield and intraline predictors are simulated. Of these, three predictors with small variances of the prediction error are combined with 4 and 3 bit Max quantizers for further processing and transmission in a TDM format. The data compression algorithms have been applied to color test pictures and their effectiveness is compared on the basis of quantitative criteria. The bandwidth reduction technique results in digital transmission of a single color TV signal at 32–43 Mbits/s. Copyright © 1984 by The Institute of Electrical and Electronics Engineers. Inc.

关键词： Predictive coding TV Band pass filters Signal processing Demodulation Color Bandwidth Frequency compression algorithms Predictive models

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Bandwidth reduction and image distortion characteristics of the LMS image compression algorithm

Bandwidth reduction and image distortion characteristics of ...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： S. Alexander S. Rajala Electrical and Computer Engineering Department North Carolina State University Raleigh NC USA

The Least Mean Squares (LMS) Algorithm may be used to adapt the coefficients of an adaptive prediction filter for image source encoding. It is shown that if one allows a small amount of distortion in the received image, then the LMS algorithm allows a dramatic reduction in the required channel transmission bandwidth. Results are presented which show LMS provides up to a 1-2 bits per symbol reduction in transmitted bit rate (compared to DPCM) when distortion levels are approximately the same in both cases. Further, LMS can equivalently be used in fixed channel bandwidth environments to decrease the image distortion. When compared to results for fixed coefficient DPCM, one is able to reduce reconstructed image distortion by as much as 7-10 dB using LMS.

关键词： Bandwidth Least squares approximation Image coding Image reconstruction Bit rate Data compression Adaptive systems Image databases compression algorithms Adaptive filters

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A DOUBLE-ADAPTIVE FILE compression ALGORITHM

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IEEE TRANSACTIONS ON COMMUNICATIONS 1983年第11期31卷 1253-1255页

作者： LANGDON, GG RISSANEN, JJ IBM Corporation San Jose CA USA

We describe a one-pass compression scheme which presumes no statistical properties of the data being compressed. The model structure adaptively selects a subset of first-order Markov contexts, based on an estimate of the candidate context's popularity. The probability distributions for the unselected (lumped) first-order contexts are made the same, reducing cost over a full first-order Markov model. Symbol repetitions are handled in special secondorder Markov contexts. The statistics for each symbol are adaptively determined by an extension of earlier work.

关键词： compression algorithms Pulse shaping methods Symmetric matrices Shape Context modeling Image coding Piecewise linear techniques Statistics Lapping Constraint optimization

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