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Circuits and Systems for Video Technology, IEEE Transactions on

Issue 6 • Date Oct 1998

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Displaying Results 1 - 9 of 9
  • Second-order derivative-based smoothness measure for error concealment in DCT-based codecs

    Page(s): 713 - 718
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    We study the recovery of lost or erroneous transform coefficients in image and video communication systems employing discrete cosine transform (DCT)-based codecs. Previously, we have developed a technique that exploits the smoothness property of image signals and recovers the damaged blocks by maximizing a smoothness measure. There, the first-order derivative was used as the smoothness measure, which can lead to the blurring of sharp edges. In order to alleviate this problem, we propose to use second-order derivatives as the smoothness measure. Our simulation results show that a weighted combination of the quadratic variation and the Laplacian operator can significantly reduce the blurring across the edges while enforcing smoothness along the edges View full abstract»

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  • A real-time system for video surveillance of unattended outdoor environments

    Page(s): 697 - 704
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    This paper describes a visual surveillance system for remote monitoring of unattended outdoor environments. The system, which works in real time, is able to detect, localize, track, and classify multiple objects moving in a surveilled area. The object classification task is based on a statistical morphological operator, the statistical pecstrum (called specstrum), which is invariant to translations, rotations, and scale variations, and it is robust to noise. Classification is performed by matching the specstrum extracted from each detected object with the specstra extracted from multiple views of different real object models contained in a large database. Outdoor images are used to test the system in real functioning conditions. Performances about good classification percentage, false and missed alarms, viewpoint invariance, noise robustness, and processing time are evaluated View full abstract»

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  • New motion estimation algorithm using adaptively quantized low bit-resolution image and its VLSI architecture for MPEG2 video encoding

    Page(s): 734 - 744
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    This paper describes a new motion estimation algorithm that is suitable for hardware implementation and substantially reduces the hardware cost by using a low bit-resolution image in the block matching. In the low bit-resolution image generation, adaptive quantization is employed to reduce the bit resolution of the pixel values, which is better than simple truncation of the least significant bits in preserving the dynamic range of the pixel values. The proposed algorithm consists of two search steps: in the low-resolution search, a set of candidate motion vectors is determined, and in the full-resolution search, the motion vector is found from these candidate motion vectors. The hardware cost of the proposed algorithm is 1/17 times of the full search algorithm, while its peak signal-to-noise ratio is better than that of the 4:1 alternate subsampling for the search range of ±32×±32. A VLSI architecture of the proposed algorithm is also described, which can concurrently perform two prediction modes of the MPEG2 video standard with the search range of (-32.0,-32.0)-(+31.5,+31.5). We fabricated a MPEG2 motion estimator with a 0.5-μm triple-metal CMOS technology. The VLSI chip includes 110 K gates of random logic and 90 K bits of SRAM in a die size of 11.5 mm×12.5 mm. The full functionality of the fabricated chip was confirmed with an MPEG2 encoder chip View full abstract»

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  • A method for watermark casting on digital image

    Page(s): 775 - 780
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    Watermark casting on digital images is an important problem since it affects many aspects of the information market. We propose a method for casting digital watermarks on images, and we analyze its effectiveness. The satisfaction of some basic demands in this area is examined, and a method for producing digital watermarks is proposed. Moreover, issues like immunity to subsampling and image-dependent watermarks are examined, and simulation results are provided for the verification of the above-mentioned topics View full abstract»

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  • Fast overlapped block motion compensation with checkerboard block partitioning

    Page(s): 705 - 712
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    The overlapped block motion compensation (OBMC) scheme provides an effective way to reduce blocking artifacts in video coding. However, in comparison with the traditional block motion compensation (BMC), its complexity of motion estimation increases significantly due to the interdependency of motion vectors. In this work, a new fast motion estimation algorithm is proposed for OBMC based on the checkerboard block partitioning and grouping in encoding. This algorithm, called the grouped OBMC (GOBMC), effectively decorrelates dependency among OBMC motion vectors and facilitates the search process. In comparison with traditional iterative OBMC motion search, GOBMC performs motion estimation only once per macroblock at the encoder, and reaches a local optimal solution with degradation of 0.05-0.1 dB. At the decoding end, we also propose a fast OBMC reconstruction scheme which reduces the complexity of multiplication to 38% of that of traditional OBMC reconstruction while preserving the same visual quality as obtained via BMC search with OBMC reconstruction View full abstract»

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  • Program transformation strategies for memory size and power reduction of pseudoregular multimedia subsystems

    Page(s): 719 - 733
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    A program transformation strategy is presented that is able to reduce the buffer size and power consumption for a relatively large class of (pseudo)regular data-dominated signal processing algorithms. Our methodology is targeted toward an implementation on programmable processors, but most of the principles remain valid for a custom processor implementation. As power and area cost are crucial in the context of embedded multimedia applications, this strategy can be very valuable. The feasibility of our approach is demonstrated on a representative high-speed video processing algorithm for which we obtain a substantial reduction of the area and power consumption compared to the classical approaches View full abstract»

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  • Fixed-length entropy coding for robust video compression

    Page(s): 745 - 755
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    Entropy coding is a fundamental stage in all video compression algorithms in terms of compression efficiency and error resilience. Variable-length entropy codes (VLC) are used in current video codecs. Designed to be employed in noiseless applications, these codes are very sensitive to transmission errors. This paper proposes the use of fixed-length entropy codes (FLC) as an alternative to VLC in video compression applications. In noisy transmissions, the FLC-based codec has shown a superior performance compared to VLC-based codecs with synchronization words, while matching its performance in terms of coding efficiency View full abstract»

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  • Tracking textured deformable objects using a finite-element mesh

    Page(s): 756 - 774
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    This paper presents an algorithm for the estimation of the motion of textured objects undergoing nonrigid deformations over a sequence of images. An active mesh model, which is a finite-element deformable membrane, is introduced in order to achieve efficient representation of global and local deformations. The mesh is constructed using an adaptive triangulation procedure that places more triangles over high detail areas. Through robust least squares techniques and modal analysis, efficient estimation of global object deformations is achieved, based on a set of sparse displacement measurements. A local warping procedure is then applied to minimize the intensity matching error between subsequent images, and thus estimate local deformations. Among the major contributions of this paper are novel techniques developed to acquire knowledge of the object dynamics and structure directly from the image sequence, even in the absence of prior intelligence regarding the scene. Specifically, a coarse-to-fine estimation scheme is first developed, which adapts the model to locally deforming features. Subsequently, principal components modal analysis is used to accumulate knowledge of the object dynamics. This knowledge is finally exploited to constrain the object deformation. The problem of tracking the model over time is addressed, and a novel motion-compensated prediction approach is proposed to facilitate this. A novel method for the determination of the dynamical principal axes of deformation is developed. The experimental results demonstrate the efficiency and robustness of the proposed scheme, which has many potential applications in the areas of image coding, image analysis, and computer graphics View full abstract»

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  • Automatic adaptation of a face model using action units for semantic coding of videophone sequences

    Page(s): 781 - 795
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    The topic of investigation is automatic adaptation of a face model at the beginning of a videophone sequence for implementing mimic analysis by means of action units in a semantic coder. Here, not only the face model is to be adapted to match the real face, but also initial values of action units are to be determined. In the proposed algorithm, eye and mouth features are first estimated using deformable templates. Then, the face model Candide is adapted to these estimated features in three steps, namely: (1) the global adaptation; (2) the local adaptation; and (3) the mimic adaptation. For the mimic adaptation, six action units are used and their initial values are determined. The proposed adaptation algorithm differs from previous works in the following aspects: (1) there is no restriction on the rotation for the global adaptation of the face model and (2) initial values of action units are determined due to the mimic adaptation. The proposed algorithm has been experimented onto synthetic images and natural head-and-shoulder videophone sequences with a spatial resolution corresponding to CIF and a frame rate of 10 Hz. The average errors for the estimation of eye and mouth features and for the adaptation of the face model amount to 1.936 (pel) and 2.009 (pel), respectively. With this adaptation algorithm, mimic analysis for semantic coding by means of action units in the subsequent frames is realizable 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