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EFFICIENCY ANALYSIS AND APPLICATION OF UNCOVERED BACKGROUND PREDICTION IN A LOW BIT RATE IMAGE codeR

IEEE TRANSACTIONS ON COMMUNICATIONS 1990年第9期38卷 1578-1584页

作者： HEPPER, D UNIV HANOVER INST THEORET NACHRICHTENTECH & INFORMAT VERARBEITUNGW-3000 HANOVER 1GERMANY

A fast algorithm for gaining scene background information from a TV sequence is presented. This picture information is used by an uncovered background predictor in a motion-compensating predictive coder for videoconference or picture telephone applications. In uncovered background regions, prediction error entropy is reduced close to the value of the frame difference entropy in static regions, which is regarded as a practical lower bound. Almost all these picture elements can therefore be reconstructed without transmission. A motion-compensating hybrid differential pulse-code modulation (hybrid-DPCM)/transform coder is supplemented by uncovered background prediction. The maximum bit rate reduction achieved in the experiments is 9% for a picture where 14% of the picture elements of temporally changed regions belong to uncovered background regions.

关键词： Videoconferencing differential pulse code modulation pixel ENcodeR

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WILCOXON-MANN-WHITNEY RANK TEST-BASED FILTER FOR REMOVING STREAK NOISE IN TRANSMITTED DPCM IMAGES

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IEEE TRANSACTIONS ON COMMUNICATIONS 1990年第2期38卷 150-155页

作者： KUNDU, A WU, WR Department of Electrical and Computer Engineering SUNY Buffalo NY USA

An algorithm is described for filtering streak noise in corrupted DPCM (differential pulse code modulated) images. In this scheme, the corrupted line is detected using the Wilcoxon-Mann-Whitney nonparametric test. This test mechanism requires no PCM-update multiplexing. The corrupted line is then filtered using a likelihood ratio test and data from the previous line. Typical experimental results are provided.

关键词： pulse coding differential pulse code modulation rank tests Nonparametric test likelihood ratio test Filters

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POLARIZATION SELF-modulation AT MULTIGIGAHERTZ FREQUENCIES IN AN EXTERNAL-CAVITY SEMICONDUCTOR-LASER

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IEEE PHOTONICS TECHNOLOGY LETTERS 1990年第7期2卷 467-469页

作者： LOH, WH SCHREMER, AT TANG, CL School of Electrical Engineering Cornell University Ithaca NY USA

Polarization self-modulation achieved at frequencies far above the relaxation oscillation frequency in an external-cavity hybrid ring semiconductor laser without the need for any high-speed electronics is discussed. This demonstrates that polarization modulation may be a viable alternative for generating controlled signals at extremely high frequencies ( approximately=100 GHz) for use as microwave and millimeter-wave optical carriers.

关键词： polarization modulation optical carrier differential pulse code modulation Semiconductor lasers oscillation frequency MICROWAVE Relaxation oscillators Polarization Extremely high frequencies millimeter wave High-speed electronics

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ENHANCEMENT OF ONE-DIMENSIONAL VARIABLE-LENGTH DPCM IMAGES CORRUPTED BY TRANSMISSION ERRORS

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IEEE TRANSACTIONS ON COMMUNICATIONS 1989年第4期37卷 373-379页

作者： ROSE, KM HEIMAN, A CALTECH DIV COMMUN PASADENA CA 91125 USA DIGITAL EQUIPMENT PLANT DIV COMMUN IL-58102 HOLON ISRAEL

Methods are presented for enhancing one-dimensional variable-length differential pulse-code modulation (VLDPCM) images corrupted by transmission errors, are presented. The proposed methods take advantage of the VLDPCM code's high sensitivity to errors. Two methods are described. The first involves no increase of transmitted bit rate and consists of processing the corrupted image. The second method involves the transmission of additional information to enable an almost exact reconstruction of the original image. The amount of added redundancy can be reduced at the cost of performing more computations. In a simulation, the authors used less than 7% redundancy. Both methods achieve significant improvements which are demonstrated by the simulation results. The simulation results include original, corrupted, and enhanced images as well as the signal-to-noise ratio (SNR) versus bit-error rate (BER) curve. For BER 10/sup -3/, the SNR (signal-to-noise ratio) gains for the first and second methods are greater than 17 and 44 dB, respectively.

关键词： differential pulse code modulation Simulation results extra message variable length Refractive surgery enhancement Transmission errors

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A SINGLE-CHIP ADAPTIVE DPCM VIDEO codeC

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IEEE JOURNAL OF SOLID-STATE CIRCUITS 1989年第4期24卷 991-996页

作者： SCHOBINGER, M ZEHNER, B MATTHIESEN, F TOTZEK, U HARTL, J REIMANN, U Research Laboratories Siemens AG Munich Germany

A differential pulse-code modulation (DPCM) video codec with two-dimensional intrafield prediction and adaptive quantizer is presented. An approach for the arithmetic implementation of the DPCM structure and the design of a test chip, fabricated in a 1.5 mu m CMOS technology, is described. This is the first VLSI realization of a DPCM codec with adaptive quantizer. For the test chip transmitter or receiver mode, application as part of a three-dimensional interframe codec and processing of luminance or chrominance signals are optional. A line buffer and ten different quantizer characteristics are realized on-chip. Correct operation has been verified up to 26 MHz.

关键词： differential pulse code modulation line buffer quantizer luminance test chip codecs

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ADAPTIVE PREDICTIVE IMAGE-CODING USING LOCAL CHARACTERISTICS

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IEE PROCEEDINGS-I COMMUNICATIONS SPEECH AND VISION 1989年第6期136卷 385-390页

作者： HSIEH, CH LU, PC LIOU, WG Department of Electrical Engineering Chung Cheng Institute of Technology Ta-Hsi Republic of China

The paper presents an efficient adaptive predictive coding method using the local characteristics of images. In this method, three coding schemes, namely, mean, subsampling combined with fixed DPCM, and ADPCM/PCM, are used and one of these is chosen adaptively based on the local characteristics of images. The prediction parameters of the 2-d linear predictor in the ADPCM/PCM are extracted on a block by block basis using the 2-d lattice filtering method. The order update 2-d lattice model proposed by Parker and Kayran is extended into order update and time update recursion for more efficient computation. Simulation results show that the proposed method is effective in reducing the slope overload distortion and the granular noise at low bit rates, and thus it can improve the visual quality of reconstructed images. Other advantages of this method are the low computational burden and the suitability for the VLSI implementation.

关键词： PCM adaptive differential pulse code modulation DPCM Pattern recognition VLSI implementation granular noise slope overload distortion codes picture processing filtering and prediction theory adaptive predictive image coding encoding pulse-code modulation local characteristics Optical information, image and video signal processing 2D linear predictor low bit rates prediction parameters visual quality reconstructed images differential pulse code modulation adaptive filters 2D lattice filtering time update recursion order update recursion ADPCM/PCM

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QUANTIZED CONTROL USING differential ENCODING

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OPTIMAL CONTROL APPLICATIONS & METHODS 1984年第1期5卷 69-83页

作者： FISCHER, TR TINNIN, DJ MEAD OFF SYST RICHARDSONTX 75081

A vector generalization of differential pulse code modulation is used to provide quantization of control and measurements in a closed-loop control system. Algorithms are developed for the adaptive quantizer and predictor. Explicit expressions are derived for the quantization and estimation errors resulting from the differential encoding. Simulation results are presented which demonstrate that even for very low bit rates the quantized control performance is very close to the performance of the unquantized optimal control solution.

关键词： Digital control Linear-quadratic regulators differential pulse code modulation Control and measurement quantization

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INTERACTION BETWEEN LIGHT-BEAMS IN THERMOCAPILLARY LIQUID-MEDIA

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JOURNAL OF OPTICS-NOUVELLE REVUE D OPTIQUE 1983年第4期14卷 179-188页

作者： DACOSTA, G BENTOLILA, F RUIZ, E GALAN, H Dept. de Phys. Univ. Simon-Bolivar Caracas Venezuela

The free surface of a thermocapillary liquid is heated by irradiation with a Gaussian laser beam. The free surface passes by an earlier dilatation stage, followed by the formation of a pit. The surface deformation modulates in turn the phase of the reflected and transmitted beams. This phenomenon belongs to the domain of self-modulation of light beams by interaction with a material medium. The dynamics of formation of a complex depression is studied experimentally and numerically.

关键词： formation differential pulse code modulation light beams digitally Dielectric liquids Irradiation Phase gaussian laser beam surface deformation Free surfaces

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SUBJECTIVE EFFECTS OF DPCM ERRORS AND PREDICTOR LEAK ON VISUAL TELEPHONE PICTURES

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PROCEEDINGS OF THE INSTITUTION OF ELECTRICAL ENGINEERS-LONDON 1977年第9期124卷 737-742页

作者： KITCHEN, JA NICOL, RC CORBETT, JM PO RES CTR SUFFOLK IP5 7REENGLAND

A technique for reducing the visibility of transmission errors in television signals which have been digitally encoded using differential pulse-code modulation(d.p.c.m.) is to weight the predicted value of the signal by a factor less than unity. This prediction ‘leak’ has the effect of reducing the extent of the propagation, and hence the visibility, of transmission errors, but it may also increase the quantising distortion. A closely controlled subjective investigation of this error visibility against quantising distortion trade-off is described. Details of both the equipment and procedure followed are given and a mathematical model is derived to allow the plotting of curves of constant impairment for varying leak factor and error rate. The investigation indicated that for moderate channel error rates, a leak factor of 15/16 is a good compromise between error visibility and quantisation distoration.

关键词： digital encoding mathematical model visual telephone pictures video signals pulse-code modulation television signals moderate channel error rates digital communication systems transmission errors Telephony videotelephony error visibility coding errors predictor leak digital signals quantising distortion Applications of television systems differential pulse code modulation electric distortion modelling encoding

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