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Circuits and Systems for Video Technology, IEEE Transactions on

Issue 1 • Date Feb 2000

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Displaying Results 1 - 19 of 19
  • Model-based edge reconstruction for low bit-rate wavelet-compressed images

    Page(s): 120 - 132
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    At low bit rates, wavelet-based image coding is superior to most traditional block-based methods in terms of visibility and severity of coding artifacts in coded images. However, the compressed images still suffer from obvious distortions around sharp edges, which are perceptually objectionable. In order to improve the image quality for low bit-rate wavelet-based image coding, we proposed a model-based edge-reconstruction algorithm for recovering the lossy edges in coded images. Our approach applies a general model to represent varieties of edges existing in an image. Based on this model, the edge degradation process due to quantization errors of wavelet coefficients is analyzed with the characterization of two kinds of artifacts at edges. We develop two operations, model-based edge approximation and Gaussian smoothing, to reconstruct distorted edges by reducing both artifacts respectively. The proposed method is able to improve the image quality in terms of both visual perception and image fidelity (peak signal-to-noise ratio) for most images coded by wavelet-based methods at low bit-rates View full abstract»

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  • A DCT-based spatially adaptive post-processing technique to reduce the blocking artifacts in transform coded images

    Page(s): 36 - 41
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    We propose a discrete cosine transform (DCT)-based post-processing technique to alleviate the blocking artifacts in transform coded images. In our approach, the high-frequency components, mainly caused by the edge components, are examined through two steps. First, two adjacent homogeneous blocks from the block boundary are found, where the homogeneous block is defined as the block in which no adjacent pixels' difference is larger than the difference of the block boundary. Second, the local frequency characteristics in the homogeneous block are examined through the DCT. Then, we derive the relation between the DCT coefficients of two homogeneous blocks of different sizes. By considering the information about the original edge and the relation, we can detect the high-frequency components, mainly caused by the blocking artifact. The performance of the proposed technique is evaluated on both still and moving images. The simulation results indicate that the proposed technique reduces the blocking artifacts effectively and preserves the original edges faithfully, and its performance is very robust to the degree of degradation in the decoded images View full abstract»

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  • An analytically tractable model for video conference traffic

    Page(s): 63 - 67
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (100 KB)  

    We propose an analytically tractable approach to model compressed video traffic called C-DAR(1). The C-DAR(1) model combines an approach utilizing a discrete-time Markov chain with a continuous-time Markov chain. We show that this approach accurately models the distribution and exponential autocorrelation characteristics of video conferencing traffic. Also, we show that by comparing our analytical results against a simulation using actual video conferencing data, our model provides realistic results. In addition to presenting this new approach, we address the effects of long-range dependencies (LRD) in the video traffic. Based on our analytical and simulation results, we are able to conclude that the LRD have minimal impact on videoconference traffic modeling View full abstract»

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  • A new multidimensional recursive architecture for computing the discrete cosine transform

    Page(s): 113 - 119
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB)  

    This paper presents a novel recursive algorithm for generating higher order multidimensional (m-D) discrete cosine transform (DCT) by combining the computation of 2m identical lower order (smaller size) DCT architectures. One immediate outcome of our results is the true “scalability” of the DCT computation. Basically, an m-D DCT computation can be constructed from exactly one stage of smaller DCT computations of the same dimension. This is useful for both hardware and software solutions, in which a very efficient smaller size m-D DCT core has been developed, and a larger DCT computation is required. The resulting DCT networks have very simple modular structure, highly regular topology, and use simple arithmetic units View full abstract»

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  • Efficient drift-free signal-to-noise ratio scalability

    Page(s): 70 - 82
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    Signal-to-noise ratio (SNR) scalability has been incorporated into the MPEG-2 video-coding standard to allow for the delivery of two services with the same spatial and temporal resolution but different levels of quality. In this paper, we begin by reviewing the performance of a single-loop SNR scalable encoder that is compliant with the MPEG-2 standard and demonstrate that its performance is limited by drift in the base layer. We also look at an alternative single-loop drift-free noncompliant SNR scalable encoder, but discover that its coding efficiency is poor. We then review the performance of an MPEG-compliant two-loop SNR scalable encoder. Finally, we propose a new two-loop noncompliant encoder which achieves improved coding performance at the expense of some increase in encoder and decoder complexity View full abstract»

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  • A practical methodology for guaranteeing quality of service for video-on-demand

    Page(s): 166 - 178
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB)  

    A novel and simple approach for defining end-to-end quality of service (QoS) in video-on-demand (VoD) services is presented. Using this approach, we derive a schedulable region for a video server which guarantees end-to-end QoS, where a specific QoS required in the video client translates into a QoS specification for the video server. Our methodology is based on a generic model for VoD services, which is extendible to any VoD system. In this kind of system, both the network and the video server are potential sources of QoS degradation. Specifically, we examine the effect that impairments in the video server and video client have on the video quality perceived by the end user. The Columbia VoD testbed is presented as an example to validate the model through experimental results. Our model can be connected to network QoS admission control models to create a unified approach for admission control of incoming video requests in the video server and network View full abstract»

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  • Fast VQ encoding by an efficient kick-out condition

    Page(s): 59 - 62
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (92 KB)  

    A new fast approach to the nearest codeword search using a single kick-out condition is proposed. The nearest codeword found by the proposed approach is identical to the one found by the full search, although the processing time is much shorter. The principle is to bypass those codewords which satisfy the proposed kick-out condition without the actual (and time-consuming) computation of the distortions from the bypassed codewords to the query vector. Due to the efficiency and simplicity of the proposed condition, a considerable saving of the central processing unit time needed to encode a data set (using a given codebook) can be achieved. Moreover, the memory requirement is low. Comparisons with some previous works are included to show these two benefits View full abstract»

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  • Corrections to “Hybrid error concealment schemes for broadcast video transmission over ATM networks”

    Page(s): 68 - 69
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    In the original paper (see ibid., vol.9, no.6, p.868-81, Sept. 1999) some of the figures did not appear as intended by the authors. The correct versions of the figures are given here View full abstract»

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  • Adaptive model-driven bit allocation for MPEG video coding

    Page(s): 147 - 157
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    We present an adaptive model-driven bit-allocation algorithm for video sequence coding. The algorithm is based on a parametric rate-distortion model, and facilitates both picture-and macroblock-level bit allocation. A region classification scheme is incorporated into the algorithm, which exploits characteristics of human visual perception to efficiently allocate bits according to a region's visual importance. The application of this algorithm to MPEG video coding is discussed in detail. We show that the proposed algorithm is computationally efficient and has many advantages over the MPEG-2 TM5 bit-allocation algorithm View full abstract»

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  • Performance characterization of video-shot-change detection methods

    Page(s): 1 - 13
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    A number of automated shot-change detection methods for indexing a video sequence to facilitate browsing and retrieval have been proposed. Many of these methods use color histograms or features computed from block motion or compression parameters to compute frame differences. It is important to evaluate and characterize their performance so as to deliver a single set of algorithms that may be used by other researchers for indexing video databases. We present the results of a performance evaluation and characterization of a number of shot-change detection methods that use color histograms, block motion matching, or MPEG compressed data View full abstract»

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  • Design of SC filters for video applications

    Page(s): 14 - 22
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    This work examines the practical issues concerning the realization of switched-capacitors video-rate finite-impulse response filters based on standard CMOS technology. The capacitor spread/sensitivity tradeoff is explored for a number of architectural solutions and an architecture suitable to the challenges of the video field is identified. The nonidealities of switches and operational amplifiers, which must be accounted for at video-rate, are analyzed and practical solutions to prevent performance deterioration are proposed. The implementation of a concrete design case is discussed and presented as a demonstration of the technological solutions proposed View full abstract»

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  • Buffer analysis and control in CBR video transcoding

    Page(s): 83 - 92
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB)  

    In video distribution services, various networks of different capacity may be linked together to form the branches of a multicasting tree. In order to efficiently use the available bandwidth of each subnetwork, a video transcoder capable of reducing the bit rate of the incoming bit stream must be used at those nodes whose output links have less bandwidth than the input one. In this paper, we analyze the buffering implications of inserting a video transcoder within the transmission path. For transcoders with either fixed or variable compression ratio, we show that the encoder buffer size can be maintained as if no transcoder existed while the decoder has to modify its own buffer size according to both the bit rate conversion ratio and transcoder buffer size. We derive the conditions that have to be met by both the encoder and transcoder buffers for preventing the decoder buffer from underflowing or overflowing. Furthermore, based on the characteristics of constant bit rate (CBR) MPEG coded video, we show that efficient bit rate control can be implemented in CBR video transcoders such that the picture quality of transcoded sequences is practically the same as those directly encoded from the original sequence at the same reduced bit rates View full abstract»

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  • Rapid estimation of camera motion from compressed video with application to video annotation

    Page(s): 133 - 146
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    As digital video becomes more pervasive, efficient ways of searching and annotating video according to content will be increasingly important. Such tasks arise, for example, in the management of digital video libraries for content-based retrieval and browsing. We develop tools based on camera motion for analyzing and annotating a class of structured video using the low-level information available directly from MPEG-compressed video. In particular, we show that in certain structured settings, it is possible to obtain reliable estimates of camera motion by directly processing data easily obtained from the MPEG format. Working directly with the compressed video greatly reduces the processing time and enhances storage efficiency. As an illustration of this idea, we have developed a simple basketball annotation system which combines the low-level information extracted from an MPEG stream with the prior knowledge of basketball structure to provide high-level content analysis, annotation, and browsing for events such as wide-angle and close-up views, fast breaks, probable shots at the basket, etc. The methods used in this example should also be useful in the analysis of high-level content of structured video in other domains View full abstract»

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  • Efficient modeling of VBR MPEG-1 coded video sources

    Page(s): 93 - 112
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    The performance evaluation of broadband networks requires statistical analysis and modeling of the actual network traffic. Since multimedia services, and especially variable bit rate (VBR) MPEG-coded video streams are expected to be a major traffic component carried by these networks, modeling of such services and accurate estimation of network resources are crucial for proper network design and congestion-control mechanisms that can guarantee the negotiated quality of service at a minimum cost. The layer modeling of MPEG-1 coded video streams and statistical analysis of their traffic characteristics at each layer is proposed, along with traffic models capable of estimating the network resources over asynchronous transfer mode (ATM) links. First, based on the properties of the entire MPEG-1 sequence (frame layer signal), a model (Model A) is presented by correlating three stochastic processes in discrete time (autoregressive models), each of which corresponds to the three types of frames of the MPEG encoder (I, P, and B frames). To simplify the traffic Model A and to reduce the required number of parameters, we study the MPEG stream at a higher layer by considering a signal, which expresses the average properties of I, P, and B frames over a group of picture (GOP) period. However, models on this layer cannot accurately estimate the network resources, especially in multiplexing schemes. For this reason, an intermediate layer is introduced, which exploits and efficiently combines information of both the aforementioned layers, producing a model (Model B), which requires much smaller number of parameters than Model A and simultaneously provides satisfactory results as far as the network resources are concerned. Evaluation of the validity of the proposed models is performed through experimental studies and computer simulations, using several long duration VBR MPEG-1 coded sequences, different from that used in modeling. The results indicate that both Models A and B are good estimators of video traffic behavior over ATM links at a wide range of utilization View full abstract»

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  • Three-sided side match finite-state vector quantization

    Page(s): 51 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    Several low bit-rate still-image compression methods have been presented, such as SPHIT, hybrid VQ, and the Wu-Chen (see Proc. IEEE ICASSP, 1997) method. In particular, the image “Lena” can be compressed using less than 0.15 bpp at 31.4 dB or higher. These methods exercise the analysis techniques (wavelet or subband) before distributing the bit rate to each piece of an image, thus the dilemma between bit rate and distortion can be solved. In this paper, we propose a simple but comparable method that adopts the technique of side match VQ only. The side match vector quantization (SMVQ) is an effective VQ coding scheme at low bit-rate. The conventional side match (two-sided) VQ utilizes the codeword information of two neighboring blocks to predict the state codebook of an input vector. We propose a hierarchical three-sided side match finite-state vector quantization (HTSMVQ) method that can: (1) make the state codebook size as small as possible-the size is reduced to one if the prediction can perform perfectly; (2) improve the prediction quality for edge blocks; and (3) regularly refresh the codewords to alleviate the error propagation of side match. In the simulation results, the image “Lena” can be coded with a PSNR 34.682 dB at 0.25 bpp. It is better than SPIHT, EZW, FSSQ and hybrid VQ with 34.1, 33.17, 33.1, and 33.7 dB, respectively. At a bit rate lower than 0.15 bpp, only the enhanced version of EZW performs better than our method, at about 0.14 dB View full abstract»

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  • Adaptive intra block update for robust transmission of H.263

    Page(s): 30 - 35
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (96 KB)  

    An adaptive block based intra refresh algorithm for increasing error robustness in an interframe coding system is described. The goal of this algorithm is to allow the intra update rates for different image regions to vary according to various channel conditions and image characteristics. The update scheme is based on an “error-sensitivity metric,” accumulated at the encoder, representing the vulnerability of each coded block to channel errors. As each new frame is encoded, the accumulated metric for each block is examined, and those blocks deemed to have an unacceptably high metric are sent using intra coding as opposed to inter coding. This approach requires no feedback channel and is fully compatible with H.263. It involves a negligible increase in encoder complexity and no change in the decoder complexity. Simulations performed using an H.263 bitstream corrupted by channel errors demonstrate a significant improvement in terms of error recovery time over nonadaptive intra update strategies View full abstract»

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  • Rigid 3-D motion estimation using neural networks and initially estimated 2-D motion data

    Page(s): 158 - 165
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    This paper extends a known efficient technique for rigid three-dimensional (3-D) motion estimation so as to make it applicable to motion estimation problems occuring in image sequence coding applications. The known technique estimates 3-D motion using previously evaluated 3-D correspondence. However, in image sequence coding applications, 3-D correspondence is unknown and usually only two-dimensional (2-D) motion vectors are initially available. The novel neural network (NN) introduced in this paper uses initially estimated 2-D motion vectors to estimate 3-D rigid motion, and is therefore suitable for image sequence coding applications. Moreover, it is shown that the NN introduced in this paper performs extremely well even in cases where 3-D correspondence is known with accuracy. Experimental results are presented for the evaluation of the proposed scheme View full abstract»

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  • Reliable motion detection/compensation for interlaced sequences and its applications to deinterlacing

    Page(s): 23 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    We present a new method for the motion detection/compensation between opposite parity fields in interlaced video sequences. We introduce a phase-correction filter, which is applied to one type (even or odd) of fields before motion detection/compensation. By means of this phase-correction filter, the motion-compensated PSNR has been improved by more than 2 dB, on average. We also present a new deinterlacing algorithm based on the newly developed motion detection/compensation. This algorithm requires storing one field only, and the phase-corrected field is used for both motion detection/compensation and intrafield deinterlacing, thus making the proposed algorithm computationally very efficient. Excellent deinterlacing results have been obtained View full abstract»

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  • Quadtree-structured variable-size block-matching motion estimation with minimal error

    Page(s): 42 - 50
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    This paper reports two efficient quadtree-based algorithms for variable-size block matching (VSBM) motion estimation. The schemes allow the dimensions of blocks to adapt to local activity within the image, and the total number of blocks in any frame can be varied while still accurately representing true motion. This permits adaptive bit allocation between the representation of displacement and residual data, and also the variation of the overall bit-rate on a frame-by-frame basis. The first algorithm computes the optimal selection of variable-sized blocks to provide the best-achievable prediction error under the fixed number of blocks for a quadtree-based VSBM technique. The algorithm employs an efficient dynamic programming technique utilizing the special structure of a quadtree. Although this algorithm is computationally intensive, it does provide a yardstick by which the performance of other more practical VSBM techniques can be measured. The second algorithm adopts a heuristic way to select variable-sized square blocks. It relies more on local motion information than on global error optimization. Experiments suggest that the effective use of local information contributes to minimizing the overall error. The result is a more computationally efficient VSBM technique than the optimal algorithm, but with a comparable prediction error View full abstract»

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Aims & Scope

The emphasis is focused on, but not limited to:
1. Video A/D and D/ A
2. Video Compression Techniques and Signal Processing
3. Multi-Dimensional Filters and Transforms
4. High Speed Real-Tune Circuits
5. Multi-Processors Systems—Hardware and Software
6. VLSI Architecture and Implementation for Video Technology 

 

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Dan Schonfeld
Multimedia Communications Laboratory
ECE Dept. (M/C 154)
University of Illinois at Chicago (UIC)
Chicago, IL 60607-7053
tcsvt-eic@tcad.polito.it

Managing Editor
Jaqueline Zelkowitz
tcsvt@tcad.polito.it