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Selected Areas in Communications, IEEE Journal on

Issue 7 • Date August 1987

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Displaying Results 1 - 16 of 16
  • [Back cover]

    Publication Year: 1987 , Page(s): 0
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    Freely Available from IEEE
  • [Front cover and table of contents]

    Publication Year: 1987 , Page(s): 0
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    Freely Available from IEEE
  • Guest Editorial: Low Bit-Rate Coding of Moving Images

    Publication Year: 1987 , Page(s): 1065 - 1067
    Cited by:  Papers (4)
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    Freely Available from IEEE
  • Improvements of Transform Coding Algorithm for Motion-Compensated Interframe Prediction Errors-DCT/SQ Coding

    Publication Year: 1987 , Page(s): 1068 - 1078
    Cited by:  Papers (24)  |  Patents (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1336 KB)  

    A new hybrid coding method for transmitting videoconferencing images at a bit rate 384 kbits/s is proposed. Considering the characteristics of motion-compensated interframe prediction errors for typical videoconferencing scenes, a filter is introduced to separate pulsive components on which conventional discrete cosine transform (DCT) coding method does not work well. These separated pulsive components are coded by using scalar quantization (SQ). The remainder are DCT coded. For DCT coefficients, an adaptive coding method based on the classification of DCT coefficients is applied in order to improve the coding performance. Since the proposed method employs both DCT coding and SQ of prediction errors, it is named "DCT/SQ coding method." Experimental results show that the DCT/SQ coding method is effective to reduce so-called mosquito effects, and thus it can improve the quality of decoded images. View full abstract»

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  • Entropy Coding for a Hybrid Scheme with Motion Compensation in Subprimary Rate Video Transmission

    Publication Year: 1987 , Page(s): 1166 - 1174
    Cited by:  Papers (3)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (808 KB)  

    Entropy coding has been investigated for motion-compensated interframe (MC) prediction followed by two-dimensional discrete cosine transform (DCT) for prediction error. In particular, variable word length coding methods for motion vector and transform coefficients have been discussed assuming low bit rate such as 384 kbits/s for transmission of videoconference sequences. For motion vector information, it is advantageous to employ a one-dimensional code set common to both horizontal and vertical components of motion vectors. The code set can be obtained using a combined distribution of the two components. In order to encode transform coefficients, different methods are applied to significant and insignificant blocks. Run-length coding is adequate for representing clusters of insignificant blocks. In encoding transform coefficients in significant blocks, a zone coding method which encodes transform coefficients within a minimum area enclosing all nonzero coefficients is suitable. Simulation of video sequences shows that a combination of the coding methods described here can achieve high coding efficiency for videoconference sequences. View full abstract»

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  • Recursive Temporal Filtering and Frame Rate Reduction for Image Coding

    Publication Year: 1987 , Page(s): 1155 - 1165
    Cited by:  Papers (4)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1232 KB)  

    The effect of temporal recursive filtering and frame rate reduction on a sequence of moving images is investigated. Following a well-known first-order Markov model for the temporal domain data, the effect of filtering and frame rate reduction on the values of variance, correlation coefficient, filtering distortion, and interframe prediction error are mathematically derived. The validity of these derivations is verified by the experimental results using a CCITT standard sequence which closely follows the first-order Markov model. The effect of temporal filtering and frame rate reduction to the coding rate is examined by encoding the CCITT standard sequence using a combined interframe and intraframe Scene Adaptive Coding system. At a frame rate of 30 frames per second, a 2:1 reduction in coding rate is obtained with a filtering coefficient of 0.5. At a frame rate of 10 frames per second, an additional reduction factor of nearly 2 is obtained using the same filtering coefficient. Selected images are presented to demonstrate the subjective effect. View full abstract»

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  • Entropy Coding for Low-Bit-Rate Visual Telecommunications

    Publication Year: 1987 , Page(s): 1175 - 1183
    Cited by:  Papers (10)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (896 KB)  

    Several compression techniques need to be integrated for the achievement of effective low-bit-rate coding of moving images. Image entropy codes are used in conjunction with either predictive or transform coding methods. In this paper, we investigate the possible advantages of using arithmetric codes for image entropy coding. A theory of source modeling is established based on the concept of source parsing and conditioning trees. The key information-theoretic properties of conditioning trees are discussed along with algorithms for the construction of optimal and suboptimal trees. The theory and algorithms are then applied to evaluating the performance of entropy coding for the discrete cosine transform coefficients of digital images from the "Walter Cronkite" video sequence. The performance of arithmetic codes is compared to that of a traditional combination of run length and Huffman codes. The results indicate that binary arithmetic codes outperform run length codes by a factor of 55 percent for low-rate coding of the zero-valued coefficients. Hexadecimal arithmetic codes provide a coding rate improvement as high as 28 percent over truncated Huffman codes for the nonzero coefficients. The complexity of these arithmetic codes is suitable for practical implementation. View full abstract»

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  • A Motion Picture Coding Algorithm Using Adaptive DCT Encoding Based on Coefficient Power Distribution Classification

    Publication Year: 1987 , Page(s): 1090 - 1099
    Cited by:  Papers (7)  |  Patents (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1400 KB)  

    A motion picture coding algorithm using motion-compensated interframe prediction and the adaptive discrete cosine transform (DCT) encoding technique is proposed. High coding efficiency is obtained by the adaptive DCT encoding technique in which encoding parameters are fitted to widely varying characteristics of the interframe differential signal. Segmented DCT subblocks of interframe prediction error are classified into categories based on their coefficient power distribution characteristics. The adaptation gain results from using a suitable variable word length code set designated by the above classification for encoding each quantization index of DCT coefficients. In addition, a new coding parameter control method is introduced based on the information rate estimation of the current frame. This classification promotes high stability because good estimation accuracy of bits consumption for each DCT subblock is obtained by utilizing the category indexes. Simulation results show that the proposed algorithm has enough coding efficiency to transmit videoconferencing motion pictures through a 384 kbit/s channel. View full abstract»

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  • A Variable Resolution Video Codec for Low Bit-Rate Applications

    Publication Year: 1987 , Page(s): 1184 - 1189
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB)  

    Demand for interpersonal video and audio communication at bit rates available on basic and subprimary ISDN accesses is growing and it is expected that service implementation will require large numbers of low-cost high-quality equipment. This paper describes the concept and simulation results of a coding scheme of the hybrid (intraframe transform and temporal DPCM) type whose main feature is the possibility of regaining high resolution for slowly changing pictures. Methods for controlling the spatio/temporal resolutions and simulation results are given. A byproduct of the algorithm allows the reduction of the transmission buffer to negligible values. View full abstract»

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  • The Efficiency of Motion-Compensating Prediction for Hybrid Coding of Video Sequences

    Publication Year: 1987 , Page(s): 1140 - 1154
    Cited by:  Papers (104)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1032 KB)  

    Performance bounds for generalized hybrid coding of video sequences with motion-compensating prediction are derived based on rate-distortion theory. It is shown that the spatial power spectrum of the motion-compensated prediction error can be calculated from the signal power spectrum and the displacement estimation error p.d.f.. A spatial Wiener filter can improve the efficiency of motion-compensating prediction. Memoryless encoding of the motion-compensated prediction error and intraframe encoding of the motion-compensated prediction error are compared. An evaluation of the rate-distortion functions for a typical videoconference sampling format shows that for integer pel accuracy of the displacement estimate the additional gain by motion-compensating prediction over pure intraframe coding is limited to ∼ 0.8 bits/sample in moving areas. Required accuracies of the displacement estimate for a gain of motion-compensating interframe coding over intraframe coding are given. View full abstract»

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  • Using Convex Set Techniques for Combined Pixel and Frequency Domain Coding of Time-Varying Images

    Publication Year: 1987 , Page(s): 1127 - 1139
    Cited by:  Papers (9)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1568 KB)  

    Projection onto convex sets has recently been suggested as an approach to time-varying image compression. In this paper, an image coding technique based on such an approach is developed. In particular, pixel and frequency domain information is combined in order to improve image quality over standard transform coding at given bit rates. The use of nonintersecting convex sets is shown to be optimum for two sets and a given error measure. Convex sets and projections are discussed in general and then in the context of image compression. Simulation results are presented for single frame images as well as for image sequences. View full abstract»

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  • Image Sequence Compression Using a Pel-Recursive Motion-Compensated Technique

    Publication Year: 1987 , Page(s): 1100 - 1114
    Cited by:  Papers (7)  |  Patents (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1552 KB)  

    This paper presents and analyzes a pel-recursive, motioncompensated, image sequence compression algorithm [1]. The analysis retains all the terms of the Taylor's series expansion and yields a set of equations for which the convergence criteria and the convergence rate of the motion estimate are more easily seen. The existing motion prediction schemes are also reviewed and a new motion prediction scheme is presented which is shown to be superior to the existing schemes. Simulations run on actual image sequences to verify the analytical results indicate that implementing the analytical model as opposed to the generally used heuristic technique does yield a decrease in the information rate and the computational requirements. Simulation results also are included which use the "projection-along-the-motiontrajectory" or PAMT prediction scheme. Third, zeroth-order entropy encoding is shown to reduce the bit rate on the order of 12 percent, and to reduce the mean square error in the reconstructed images on the order of 60 percent when compared to first-order entropy encoding. Fourth, field-to-field motion prediction is compared to frame-to-frame motion prediction. View full abstract»

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  • A Look-Up-Based Universal Real-Time Transformer for Image Coding

    Publication Year: 1987 , Page(s): 1207 - 1213
    Cited by:  Papers (1)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    A universal transformer for two-dimensional separable linear transforms in image coding is proposed. It is not restricted to fast transforms, and switching between transforms only requires writing the appropriate constants into an internal RAM. Look-up tables are used to reduce computational complexity. The linear transform properties are exploited to reduce the memory requirements by decomposing the input vector into smaller arrays and into bit planes. The input is pipelined into parallel data paths. An implementation example on a single gate array with existing technology achieves real-time transformation of 8 × 8 blocks, with area requirements of around 38K gates. View full abstract»

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  • A Low Bit-Rate Image Sequence Coder Combining a Progressive DPCM on Interleaved Rasters with a Hybrid DCT Technique

    Publication Year: 1987 , Page(s): 1079 - 1089
    Cited by:  Papers (1)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (960 KB)  

    An image sequence coding scheme for transmission at 384 kbits/s and 64 kbits/s is presented. In comparison to known schemes, picture quality in still picture areas is improved without impairing the rendition of temporally changed areas. Bit-rate reduction is obtained by a conventional hybrid DCT coding technique in changed areas, and a predictive coding technique using a raster interleaving approach to update still picture areas. Preferentially treating the image signal in still areas with a not-block-oriented coder yields in these regions a reconstruction with full spatial resolution and free of any block effects. Experimental results are presented confirming that the quality in still picture areas is improved compared to that of known low bit-rate image sequence coding schemes, while the quality in changed areas is maintained. View full abstract»

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  • Adaptive Linear Predictive Coding of Time-Varying Images Using Multidimensional Recursive Least Squares Ladder Filters

    Publication Year: 1987 , Page(s): 1115 - 1126
    Cited by:  Papers (7)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1520 KB)  

    This paper presents several adaptive linear predictive coding techniques based upon extension of recursive ladder filters to two and three dimensions (2-D/3-D). A 2-D quarter-plane autoregressive ladder filter is developed using a least square criterion in an exact recursive fashion. The 2-D recursive ladder filter is extended to a 3-D case which can adaptively track the variation of both spatial and temporal changes of moving images. Using the 2-D/3-D ladder filters and a previous frame predictor, two types of adaptive predictor-control schemes are proposed in which the prediction error at each pel can be obtained at or close to a minimum level. We also investigate several modifications of the basic encoding methods. Performance of the 2D/3-D ladder filters, their adaptive control schemes, and variations in coding methods are evaluated by computer simulations on two real sequences and compared to the results of motion compensation and frame differential coders. As a validity test of the ladder filters developed, the error signals for the different predictors are compared and the visual quality of output images is verified. View full abstract»

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  • Predictive Image Coding with Pseudo-Laplacian Edge Detector

    Publication Year: 1987 , Page(s): 1190 - 1206
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1784 KB)  

    Several edge-adaptive dual-mode predictive coding systems are proposed for coding monochrome video signals. These algorithms use the pseudo-Laplacian edge detector to switch between the textural coding and the edge coding. The one-dimensional Song DM coder and the two-dimensional weighted average prediction DM coder were used for the textural coding. The edge coding was done with either a normal two-dimensional Song DM coder, Graham's DPCM schemes, or a DPCM coder developed by the authors. Nine different combinations of textural and edge coding techniques were developed and simulated. The bit rates of the various schemes were compared, and the range varied between 2.28-3.46 bits/pixel without further compression of the edge information bits or the correction bits. Subjective tests were carried out on images reconstructed according to these schemes. The results show that most of the pictures obtained with the techniques in this paper are superior to the pictures coded by the Song mode normal two-dimensional DM coder alone. View full abstract»

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Aims & Scope

IEEE Journal on Selected Areas in Communications focuses on all telecommunications, including telephone, telegraphy, facsimile, and point-to-point television, by electromagnetic propagation.

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Editor-in-Chief
Muriel Médard
MIT