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iee International Conference on Visual Information Engineering (VIE 2005)

作者： L. J. Muir I. E. G. Richardson K. Hamilton Image Communication Technology Group The Robert Gordon University Schoolhill Aberdeen UK

Video communication systems currently provide poor quality and performance for deaf people using sign language, particularly at low bit rates. Our previous work, involving eye movement tracking experiments and analysis of visual attention mechanisms for sign language, demonstrated a consistent characteristic response which could be exploited to enable optimisation of video coding systems performance by prioritising content for deaf users. This paper describes an experiment designed to test the perceived quality of selectively prioritised video for sign language communication. A series of selectively degraded video clips was shown to individual deaf viewers. Participants subjectively rated the quality of the modified video on a Degradation Category Rating (DCR) scale adapted for sign language users. The results demonstrate the potential to develop content-prioritised coding schemes, based on viewing behaviour, which can reduce bandwidth requirements and provide best quality for the needs of the user. We propose selective quantisation to reduce compression in visually important regions of video images, which require spatial detail for small slow motion detection, and increased compression of regions regarded in peripheral vision where large rapid movements occur in sign language communication.

关键词： Assistive technology Gesture recognition Visualization Standards Spatial resolution Training Quality assessment

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Efficient video compression codebooks using SOM-based vector quantisation

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iee PROCEEDINGS-VISION image AND SIGNAL PROCESSING 2004年第2期151卷 102-108页

作者： Ferguson, KL Allinson, NM VICS Ltd Quay W Business Ctr Manchester M17 1HH Lancs England Univ Manchester Lab Image & Vis Engn Manchester M60 1QD Lancs England

A new rate-constrained self-organising map (SOM) learning algorithm, incorporating a noise-mixing model, is presented as a vector quantiser for very low bit-rate video codecs. A SOM-based approach will exhibit a higher resilience against local minima under low resolution conditions. Practical implementation details, and results are also described.

关键词： .lower bound DWT approximated codecs low bit-rate quantisation coding loop average entropy quantisers scalar quantiser

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Flexible, highly scalable, object-based wavelet image compression algorithm for network applications

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iee PROCEEDINGS-VISION image AND SIGNAL PROCESSING 2004年第6期151卷 498-510页

作者： Danyali, H Mertins, A Univ Kurdistan Dept Elect Engn Sanandaj Iran Carl von Ossietzky Univ Oldenburg Signal Proc Grp Inst Phys D-26111 Oldenburg Germany

The authors propose a highly scalable image compression scheme based on the set partitioning in hierarchical trees (SPIHT) algorithm. The proposed algorithm, called highly scalable SPIHT (HS-SPIHT), adds the spatial scalability feature to the SPIHT algorithm through the introduction of multiple resolution-dependent lists and a resolution-dependent sorting pass. It keeps the important features of the original SPIRT algorithm such as compression efficiency, full SNR scalability and low complexity. The flexible bitstream of the HS-SPIHT encoder can easily be adapted to various resolution requirements at any bit rate. The parsing process can be carried out on-the-fly without decoding the bitstream by a simple parser (transcoder) that forms a part of a smart network. The HS-SPIHT algorithm is further developed for fully scalable coding of arbitrarily shaped visual objects. The proposed highly scalable algorithm finds applications in progressive web browsing, visual databases and especially in image transmission over heterogeneous networks.

关键词： ALGORITHMS SYSTEMS design image compression INFORMATION storage & retrieval systems image transmission IMAGING systems

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Superior VLBR video coding using pattern template for moving objects instead of variable block-size in H.264

Superior VLBR video coding using pattern template for moving...

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7th International Conference on Signal Processing

作者： Paul, M Murshed, M Monash Univ Gippsland Sch Comp & IT Churchill Vic 3842 Australia

ISBN: (纸本)7121002159

The latest digital video coding standard AVC/H.264 introduced tree structured variable-block size (from 16x16 to 4x4) motion estimation and compensation to approximate the shape of the moving objects within the macroblock more accurately. The choice of different size blocks is varied as target bit rate varied. In this paper we investigate the changes of different block size for various target bit rates. Experimental results show that relatively larger blocks are selected at very low bit rate and smaller blocks are selected at higher bit rate. We also concluded that in the context of very low bit rate video coding, pattern based video coding using pattern template representations of moving objects in block-based motion estimation and compensation exhibits the superior result compare to H.264 standard.

关键词： image coding

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Content adaptive image de-blocking

Content adaptive image de-blocking

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ieeE International Symposium on Consumer Electronics

作者： Zhao, M Kneepkens, REJ Hofman, PM de Haan, G Eindhoven Univ Technol Informat & Commun Grp NL-5600 MB Eindhoven Netherlands

ISBN: (纸本)0780385268

Blocking artifacts may appear in block based digital image and video coding systems like JPEG and MPEG, especially when compression is done at a low bit-rate. The blocking artifacts can degrade the perceived image quality. In this paper, a method for reducing the blocking artifacts in the decoded image using adaptive filters is proposed The selection of the proper filter is based on the local image pattern and/or the relative pixel position in the coding block. The results show a significant image quality improvement. To evaluate the methods, both Mean Square Error (MSE) scores and Block-edge Impairment Metric (BIM) are given for objective comparison. Screen shots are also shown to demonstrate the subjective quality.

关键词： content adaptive filtering de-blocking JPEG MPEG

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New matching pursuit based sinusoidal modelling method for audio coding

New matching pursuit based sinusoidal modelling method for a...

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作者： Vera-Candeas, P. Ruiz-Reyes, N. Rosa-Zurera, M. López-Ferreras, F. Curpián-Alonso, J. Spain Spain

A new method is proposed to improve sinusoidal modelling based on energy-adaptive matching pursuits. To reduce the complexity of the algorithm, an over-complete dictionary composed of complex exponentials is used and an efficient implementation is presented. An analysis-synthesis windows scheme that avoids overlapping is also proposed. For efficient quantisation of sinusoidal model parameters, a new algorithm that significantly reduces the side information required by the decoder is described. Experimental results show the excellent performance of the proposed method for sinusoidal modelling compared to some others that are integrated into multiparts models for low bit rate audio coding applications.

关键词： Speech coding

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Mathematical properties of four wavelet filters and their performance in embedded image coders

Mathematical properties of four wavelet filters and their pe...

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7th International Conference on Signal Processing

作者： Guo, HX Su, L Yu, SS Zhou, JL Huazhong Univ Sci & Technol Dept Comp Sci & Engn Key Lab Data Storage Syst Minist Educ Wuhan 430074 Peoples R China

ISBN: (纸本)7121002159

This paper analyses the mathematical properties of four famous wavelets and evaluates their coding performance for different kinds of images in EZW image coders. It can be found that although the 9/7 bioorthogonal wavelets, which obtain better tradeoff among incompatible mathematical properties give the best performance it still can't code edges and textures efficiently due to existing ringing and smearing artifacts at low bit rates. The main reason being that every harmonic decomposition must obey the uncertainty principle, which prevents any atom perfectly well localized in the space domain to retain a frequency localization. It gives an opportunity to develop new paradigms to efficiently representing and coding structures very well localized in the space domain but with large frequency band such as edges and textures.

关键词： wavelet filters image coding embedded zerotree wavelets(EZW)

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A rate-control scheme using fast frame-rate controlling and adaptive rate-quantization modeling for H.263

A rate-control scheme using fast frame-rate controlling and ...

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2004 ieeE International Symposium on Consumer Electronics - Proceedings

作者： Chan, Din-Yuan Chang, Chun-Yuan Lin, Shou-Jen Lin, Chung-Wei Dept. of Computer Science National Chiayi University Chiayi City Taiwan Dept. of Information Engineering I-Shou University Kaohsiung Country Taiwan

ISBN: (纸本)0780385276

bit-rate control plays a critical role in the video-coding. One of the main challenges of video-coding is to provide the guaranteed quality under highly compressed video. In our study, a structured R-Q base rate-control framework is proposed for low-delay video coding, which contains three processing stages: the control of encoding frame-rate, bit-allocation for frame-level and the decision of quantization parameters for macroblock-level. First, the proposed framework decides the encoding frame-rate per group of pictures (GOPs) for better motion continuity. In the second stage, target-bit per frame is effectively estimated with the frame texture and buffer fullness. Last, based on an adaptive R-Q model modified by the Kalman filter for each cluster of MBs (COBs), a suitable quantization parameter of each MB can be confirmed. In comparison with the TMN8rc module, our new framework can achieve higher objective and perceptual quality with lower computational complexity.

关键词： image coding

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High performance video compression based on improved VSPIHT algorithm

High performance video compression based on improved VSPIHT ...

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2004 7th International Conference on Signal Processing Proceedings (ICSP'04)

作者： Jia, Hu Wengqi, Ding Liming, Zhang Dept. of Electronics Engineering Fudan University Shanghai 200433 China

This paper proposes an effective I3D-DWT-VSPIHT video coding method, which reasonably organizes wavelet coefficients by integrated 2D-SPIHT with 3D-VSPIHT, and the video sequence is partitioned into two alternate parts: original frames and residual frames, so the similar coefficients can be compressed to one or fewer symbols by sufficiently using correlation between trees, and the reconstructive image quality as well as memory saving can be improved. On the other hand, by effectively reducing redundant scan time it is available in real-time system. Simulated results show that the quality (PSNR) of reconstructed video at the same compression ratio is improved about 1 ∼ 5dB for gray video as compared with existent 3D-DWT-SPIHT. By using the high performance video compression method, available for gray and color video sequences, very low bit rate and high quality of reconstructed image can be obtained.

关键词： image compression

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Overview of compression and packet loss effects in speech biometrics

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iee PROCEEDINGS-VISION image AND SIGNAL PROCESSING 2003年第6期150卷 372-376页

作者： Besacier, L Mayorga, P Bonastre, JF Fredouille, C Meignier, S UJF IMAG CLIPS F-38041 Grenoble 9 France Univ Avignon LIA F-84911 Avignon 9 France

An overview is presented of compression and packet loss effects in speech biometrics. These new problems appear particularly in recent applications of biometrics over mobile or Internet networks. The influence of speech compression on speaker recognition performance in mobile networks is investigated. In a first experiment, it is found that the use of GSM coding degrades the performance. In a second experiment, the features for the speaker recognition system are calculated directly from the information available in the encoded bit stream. It is found that a low LPC order in GSM coding is responsible for most performance degradations. A speaker recognition system was obtained which is equivalent in performance to the original one which decodes and reanalyses speech before performing recognition. The joint packet loss and compression effects over IP networks are also studied. It is experimentally demonstrated that the adverse effects of packet loss alone are negligible, while the encoding of speech, particularly at a low bit rate, coupled with packet loss, can reduce the verification accuracy considerably.

关键词： .IP networks mobile networks speech compression compression and packet speech biometrics GSM coding

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