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Circuits and Systems for Video Technology, IEEE Transactions on

Issue 6 • Date Dec. 1995

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Displaying Results 1 - 13 of 13
  • Comment on "Estimation of shape parameter for generalized Gaussian distribution in subband decompositions of video" [with reply]

    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB)  

    In the original paper by Sharifi and Leon-Garcia (see ibid., vol.5, p. 52-56, Feb. 1995) the authors propose a method to estimate the shape parameter for a generalized Gaussian probability density function to be fitted to the subbands of a video signal. Their method, which uses certain moments of the subband histogram, has in fact already been presented some years ago by Mallat (1989). The authors reply that they thank Murching and Woods for bringing to their attention a previously published work, which has developed the method reported in their paper. They regret that their search of the previous related literature did not reveal the paper by Mallat. They note, however, that the effectiveness of the method in comparison to statistical goodness-of-fit tests, was shown in their work and not in Mallat's. View full abstract»

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  • Image segmentation using fractal coding

    Page(s): 567 - 570
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    Applying fractal coding to image segmentation was attempted as its new application. The encoding method is the same as the conventional fractal coding method, and the fractal-code is used for image segmentation. An image can be segmented by calculating basins on a dynamical system parametrized by the fractal-code. It is shown that the new method has the ability to segment regions that have fine pixel-patterns as masses View full abstract»

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  • Asymptotic limits of video signal processing architectures

    Page(s): 545 - 561
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1684 KB)  

    This paper analyzes the effects of technology scaling on video signal processing (VSP) architectures. We evaluate the processor, the memory, and the interconnect delays in terms of sophisticated delay models (that take into account deep-sub-micron device characteristics) and study how the response times of these logic components are affected when the feature sizes scale down. Equations for gate and interconnect delays, as functions of process scaling, are derived and the impact of these results examined in the context of heavily pipelined architectures, architectures featuring crossbar interconnection networks, and architectures whose performance is dominated by memory bandwidth. Architectural parameters such as clock skew, clock frequency, memory interleaving, memory efficiency, and average waiting times are analyzed in the light of the scaling behavior of the gate and the interconnect delays. In the context of scaling of interconnection lines and memory modules, we also highlight how the transmission-line characteristics of long lines are affected by technology scaling and how the delay associated with the memory subsystem-both the memory interleaving and the memory interconnect network-can be a potential bottleneck for the system's speed of operation. It is likely that sophisticated compilation and scheduling techniques must be employed along with architectural optimizations to achieve maximum system performance and ensure that the final hardware-software configuration does not overload the processor-memory communication View full abstract»

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  • A perceptually tuned subband image coder based on the measure of just-noticeable-distortion profile

    Page(s): 467 - 476
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1256 KB)  

    To represent an image of high perceptual quality with the lowest possible bit rate, an effective image compression algorithm should not only remove the redundancy due to statistical correlation but also the perceptually insignificant components from image signals. In this paper, a perceptually tuned subband image coding scheme is presented, where a just-noticeable distortion (JND) or minimally noticeable distortion (MND) profile is employed to quantify the perceptual redundancy. The JND profile provides each signal being coded with a visibility threshold of distortion, below which reconstruction errors are rendered imperceptible. Based on a perceptual model that incorporates the threshold sensitivities due to background luminance and texture masking effect, the JND profile is estimated from analyzing local properties of image signals. According to the sensitivity of human visual perception to spatial frequencies, the full-band JND/MND profile is decomposed into component JND/MND profiles of different frequency subbands. With these component profiles, perceptually insignificant signals in each subband can be screened out, and significant signals can be properly encoded to meet the visibility threshold. A new quantitative fidelity measure, termed as peak signal-to-perceptible-noise ratio (PSPNR), is proposed to assess the quality of the compressed image by taking the perceptible part of the distortion into account. Simulation results show that near-transparent image coding can be achieved at less than 0.4 b/pixel. As compared to the ISO-JPEG standard, the proposed algorithm can remove more perceptual redundancy from the original image, and the visual quality of the reconstructed image is much more acceptable at low bit rates View full abstract»

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  • Improved Huffman code tables for JPEG's encoder

    Page(s): 562 - 564
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    The article presents new tables for Huffman encoding of still images. Experimental results indicate that tables lead to an improvement of the order of 3.35% in the size of images compressed at 75% quality level and 5.3% compressed at the 50% quality level on the average View full abstract»

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  • Very low bit rate video coding using arbitrarily shaped region-based motion compensation

    Page(s): 500 - 507
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (892 KB)  

    This paper presents a novel region-based video coding algorithm for very low bit-rate transmission. A huge amount of region shape information in a conventional region-based coding does not need to be transmitted in the new approach, because it can be synchronously obtained from a reconstructed picture in both the encoder and decoder by image segmentation. Segmented region updating, which can obtain appropriate regions for motion compensated prediction, and a new bit assignment algorithm in prediction error coding are also developed. Computer simulations are carried out to evaluate the coding efficiency at 9.6 kb/s. The result indicates that the objective and subjective qualities for decoded pictures are improved compared to those for the conventional block-based method. This algorithm is significantly effective for mobile communication View full abstract»

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  • Clock recovery and reconstruction of PAL pictures for MPEG coded streams transported over ATM networks

    Page(s): 508 - 514
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    The problem of clock recovery for an MPEG audio/video decoder, when the MPEG stream is transmitted over an ATM network and the decoded signal is to be converted to a PAL/NTSC format, is addressed. The presence of ATM cell delay variation represents a jitter source for the reconstruction of the main presentation reference signals associated with the coded streams. Since the PAL/NTSC synchronization signals are obtained from these signals, care must be taken to avoid visible artifacts in the displayed images, typically hue changes. It is shown that the clock recovery design, based on consumer quality video display requirements, is not more complex than ordinary PLLs used in transmission systems, while the buffer size requirements can be certainly contained within acceptable limits View full abstract»

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  • Architectures for hierarchical and other block matching algorithms

    Page(s): 477 - 489
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1316 KB)  

    Hierarchical block matching is an efficient motion estimation technique which provides an adaptation of the block size and the search area to the properties of the image. In this paper, we propose two novel special-purpose architectures to implement hierarchical block matching for real-time applications. The first architecture is memory-efficient, but requires a large external memory bandwidth and a large number of processors. The second architecture requires significantly fewer processors, but additional on-chip memory. We describe in details the processor architecture, the memory organization and the scheduling for both these architectures. We also show how the second architecture can be modified to handle full-search and 3-step hierarchical search block matching algorithms, with significant reduction in the hardware complexity as compared to existing architectures View full abstract»

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  • Video communications using rapidly reconfigurable hardware

    Page(s): 565 - 567
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    Video coding has been implemented by using rapid reconfiguration to time share hardware for several sequential stages. This allows the chip area to be reduced by a factor proportional to the number of coding stages at the expense of some reconfiguration overhead and the added memory and control needed to implement reconfiguration. The results of this work suggest that run-time reconfiguration is a powerful technique with potential for a wide range of video applications in which temporal algorithm partitioning and rapid adaptivity are feasible and desired View full abstract»

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  • Fast and low roundoff implementation of quadrature mirror filters for subband coding

    Page(s): 524 - 532
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (748 KB)  

    We propose a fast and low roundoff-noise implementation of alias-free quadrature mirror filters (QMFs) for tree-structured subband coding. When N-tap FIR QMFs are directly utilized, they require 2N multiplications and 2(N-1) additions to obtain a pair of high-band and low-band decimated outputs. Using recursive formulas and the polyphase concept, a QMF implementation is proposed that, for both analysis and synthesis stages, needs only (N/2+2) multiplications and (3N/2+8) additions to compute the same outputs. Furthermore, the proposed algorithm can reduce roundoff error when finite-wordlength processors are used to implement the encoder and decoder. Simulation examples for image coding are also given to demonstrate the differences between the proposed and previously-known algorithms View full abstract»

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  • Improved image decompression for reduced transform coding artifacts

    Page(s): 490 - 499
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    The perceived quality of images reconstructed from low bit rate compression is severely degraded by the appearance of transform coding artifacts. This paper proposes a method for producing higher quality reconstructed images based on a stochastic model for the image data. Quantization (scalar or vector) partitions the transform coefficient space and maps all points in a partition cell to a representative reconstruction point, usually taken as the centroid of the cell. The proposed image estimation technique selects the reconstruction point within the quantization partition cell which results in a reconstructed image that best fits a non-Gaussian Markov random field (MRF) image model. This approach results in a convex constrained optimization problem that can be solved iteratively. At each iteration, the gradient projection method is used to update the estimate based on the image model. In the transform domain, the resulting coefficient reconstruction points are projected to the particular quantization partition cells defined by the compressed image. Experimental results will be shown for images compressed using scalar quantization of block DCT and using vector quantization of subband wavelet transform. The proposed image decompression provides a reconstructed image with reduced visibility of transform coding artifacts and superior perceived quality View full abstract»

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  • Image subband coding using arithmetic coded trellis coded quantization

    Page(s): 515 - 523
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1092 KB)  

    A method is presented for encoding memoryless sources using trellis coded quantization (TCQ) with uniform thresholds. The trellis symbols are entropy-coded using arithmetic coding. The performance of the arithmetic coded uniform threshold TCQ, for encoding the family of generalized Gaussian densities, is compared with uniform threshold quantization (UTQ) and the Shannon lower bound (SLB). At high rates, the method performs within 0.5 dB of the rate-distortion bound for the family of generalized Gaussian densities. A simple modification of the uniform codebook is shown to result in improved performance at low bit rates. The arithmetic and trellis coding method is used for encoding image subbands. Coding results for monochrome images are presented and compared with other results in the literature. Working C code that implements arithmetic coded uniform threshold TCQ can be obtained using anonymous ftp View full abstract»

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  • Rapid scene analysis on compressed video

    Page(s): 533 - 544
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1472 KB)  

    Several rapid scene analysis algorithms for detecting scene changes and flashlight scenes directly on compressed video are proposed. These algorithms operate on the DC sequence which can be readily extracted from video compressed using Motion JPEG or MPEG without full-frame decompression. The DC images occupy only a small fraction of the original data size while retaining most of the essential “global” information. Operating on these images offers a significant computation saving. Experimental results show that the proposed algorithms are fast and effective in detecting abrupt scene changes, gradual transitions including fade-ins and fade-outs, flashlight scenes and in deriving intrashot variations 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