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4th International ITG conference on Source and Channel Coding

作者： Schulze, Henrik Univ. of Applied Sciences Meschede D-59872 Meschede Germany

In this paper, we investigate the concetanation of Alamouti's 2-antenna space-time coding scheme with standard outer error-correcting codes. By introducing a proper matrix description, the channel can be visualized as a 4-dimensional rotation of a generalized phasor (given by the pair of transmit symbols), followed by the attenuation given by the composed fading amplitude. This interpretation makes it easy to understand that this 2-transmit (TX) antenna scheme is completely equivalent to a 2-receive (RX) antenna setup with maximum ratio combining (MRC). Analytical formulas for pair error probabilities will be derived for the time/frequency flat fading and for the ideally interleaved Rayleigh fading channel as well as for the correlated fading channel. As a practical example, we study how the performance of a Walsh-Hadamard coded multi-carrier (MC-) CDMA system depends of the correlation bandwidth of the channel and the number of RX and TX antennas.

关键词： Channel coding Diversity Fading channels Space-time coding Wireless communications

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Robust wavelet-based arbitrary grid detection for MPEG

Robust wavelet-based arbitrary grid detection for MPEG

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IEEE International conference on image processing

作者： E. Lesellier J. Jung Philips Research France France

From the industrial point of view, image quality is a key-issue. Many post-processing algorithms have been proposed to improve visual quality after the MPEG decoder. Most of them need precise location of the 8/spl times/8 grid on which the blocking effect appears. However, in real-life applications, the blocking effect is rarely located on such a basic grid, due to the cascaded bit-rate or format transcoding, rescaling, etc., that occur during acquisition, compression, transmission and display of the video. Consequently, most of these methods see their efficiency largely reduced, or are simply useless. A grid detector is proposed, based on a fine modeling of blocking artifacts in the wavelet domain. It aims at providing essential information to any post-processing algorithm that requires the position of the grid. Several experiments and reliable subjective tests demonstrate the accuracy of the proposed grid detector, and highlight the added value it yields to a post-processing algorithm in terms of visual quality.

关键词： Robustness Detectors image quality Transform coding Decoding Transcoding Displays Video compression Wavelet domain Testing

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Video clip recognition using joint audio-visual processing model

Proceedings - International Conference on Pattern Recognitio...

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Proceedings - International conference on Pattern Recognition 2002年第1期16卷 500-503页

作者： Kulesh, Victor Petrushin, Valery A. Sethi, Ishwar K. Department of Computer Science and Engineering 160 Dodge Hall Oakland University Rochester MI 48309 United States Accenture Technology Labs Accenture 3773 Willow Rd Northbrook IL 60062 United States

The automatic recognition of video clips is an important capability with applications in broadcast monitoring for content theft and adherence to advertisement campaign. In this paper, we present an approach for video clip recognition based on HMM and GMM for modeling video and audio streams respectively. The approach is used to model TV commercials. The recognition results of using single stream and joint models are compared. The error rate of 0.01% is achieved when the joint audio-visual processing model is employed. © 2002 IEEE.

关键词： image reconstruction

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A minimum distortion data hiding technique for compressed images

A minimum distortion data hiding technique for compressed im...

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IEEE Workshop on Multimedia Signal processing

作者： C. Candan N. Jayant Multimedia Communications Laboratory Georgia Institute of Technology Atlanta GA USA

We present a blind data hiding method for JPEG compressed images, which minimizes the perceptual distortion due to data embedding. The proposed system presents a number of options to the encoder to cast the given hidden bits in the compressed content signal. The perceptual distortion cost of each option is calculated from the parameters available to the encoder such as the original image, quantization error due to compression and just noticeable distortion (JND) levels of the original image derived through an empirical human visual system model. The encoder selects the option with the minimum JND cost to cast the hidden bits. By the definition of blind decoding, the decoder should be able to extract the hidden bits without any side information on the option selected or the parameters available to the encoder. The decoder of the proposed system uses simple binary addition on their received transform coefficients to extract the hidden bits blindly. System performance is examined by computer experiments at different compression levels and at different embedding bitrates.

关键词： Data encapsulation image coding Decoding Costs Data mining Transform coding Quantization Humans visual system System performance

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Why is image quality assessment so difficult?

Why is image quality assessment so difficult?

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International conference on Acoustics, Speech, and Signal processing (ICASSP)

作者： Zhou Wang Alan C. Bovik Ligang Lu Lab for Image and Video Engi. Department of ECE University of Texas Austin Austin TX USA IBM Thomas J. Watson Research Center Yorktown Heights NY USA

image quality assessment plays an important role in various image processing applications. A great deal of effort has been made in recent years to develop objective image quality metrics that correlate with perceived quality measurement. Unfortunately, only limited success has been achieved. In this paper, we provide some insights on why image quality assessment is so difficult by pointing out the weaknesses of the error sensitivity based framework, which has been used by most image quality assessment approaches in the literature. Furthermore, we propose a new philosophy in designing image quality metrics: The main function of the human eyes is to extract structural information from the viewing field, and the human visual system is highly adapted for this purpose. Therefore, a measurement of structural distortion should be a good approximation of perceived image distortion. Based on the new philosophy, we implemented a simple but effective image quality indexing algorithm, which is very promising as shown by our current results.

关键词： Distortion measurement Distortion Instruments

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Sub-picture video coding for unequal error protection

Sub-picture video coding for unequal error protection

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European Signal processing conference (EUSIPCO)

作者： Miska M. Hannuksela Ye-Kui Wang Moncef Gabbouj Nokia Mobile Phones Tampere Finland Tampere International Center for Signal Processing (TICSP). Tampere Finland Tampere University of Technology Finland

Unequal error protection is one of the key tools in video communication systems operating over error-prone networks. In order to allow unequal protection of a video bit-stream, codewords have to be categorized according to their importance to visual quality. The proposed sub-picture coding method allows partitioning images to regions of interest and helps to maintain a good image quality in the chosen regions. As an example, the sub-picture coding scheme is applied to multicast Internet streaming. It is shown that the overall subjective image quality and the objective foreground image quality are considerably better when compared to the selected conventional coding schemes.

关键词： Payloads Transform coding Streaming media Data models Error correction codes Abstracts Internet

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Robust image watermarking based on Independent Component Analysis

Robust image watermarking based on Independent Component Ana...

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International conference on Acoustics, Speech, and Signal processing (ICASSP)

作者： Dan Yu Farook Sattar Nanyang Technological University Singapore

A robust image watermarking technique based on Independent Component Analysis (ICA) is introduced in the paper. By utilizing the masking properties of the human visual system (HVS), a grayscale watermark is chosen which is found to be more robust against various attacks. Comparing with other watermarking schemes (for example, by Cox et. al. [1]), our proposed ICA based watermarking scheme can successfully extract a watermark where watermark embedding can be done either instantaneously or convolutively. Various existing ICA algorithms are employed and compared in terms of watermark extraction performance. This paper also shows the robustness in watermark extraction against some standard image processing attacks such as scaling, cropping, rotation, JPEG compression, filtering, additive noise, multiple marks and collusion.

关键词： Cryptography Watermarking Independent component analysis Robustness Transform coding

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Implementation of algorithm to decode two-dimensional barcode PDF-417

Implementation of algorithm to decode two-dimensional barcod...

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International conference on Signal processing Proceedings (ICSP)

作者： Hee Il Hahn Joung Koo Joung Department Information and Communications Engineering Hankuk University of Foreign Studies Yongin si Gyeonggi South Korea

ISBN: (纸本)0780374886

We present a barcode reader to decode two-dimensional symbology PDF-417 and propose a novel method to extract the bar-space patterns directly from the gray-level barcode image, which employs the location and the distance between extreme points of each row of the barcode image. This algorithm proves to be very robust for high convolution distortion environments such as defocussing and warping, even under bad illumination conditions. If the scanned barcode image is a result of the convolution of a Gaussian-shaped point spread function with a bilevel image, popular image segmentation methods such as image thresholding cannot distinguish between very narrow bar-space patterns which are a couple of pixels wide. The proposed algorithm shows improved performance over current barcode readers.

关键词： Decoding Databases Data mining Convolution Licenses Error correction Matrix converters Encoding Robustness Gaussian processes

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Development of "high presence" video communication system – trial experiment of the next generation real-time remote lecture – 1

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International conference on Information Networking, ICOIN 2002

作者： Komine, Takahiro Machizawa, Akihiko Nakagawa, Shin-Ichi Kubota, Fumito Tan, Yasuo Communications Research Laboratory Information and Network Systems Division 4-2-1 Nukui-Kitamachi Koganei-shi Tokyo184-8795 Japan Japan Advanced Institute of Science and Technology School of Information Science 1-1 Asahidai Tatsunokuchi Ishikawa923-1292 Japan

ISBN: (数字)9783540458012

ISBN: (纸本)3540442553

We have been developing the Next Generation remote lecture system that real-time transmits "high presence" audio/visual images (that are, as real as it feels no distance or screen is ever existing), without having any disturbance in a long distance transmission. We figured out what functions are required to perform the real-time remote lectures with multi-interaction between an instructor and students. We also reconfirmed the technical difficulties by executing the remote debate trial experiments and the distributed cardiac surgery workshop trial experiments and evaluating them. This paper presents introduces the Next Generation remote lecture system, which is developed based on the results and analysis of our past experiments, and reports the results of our first trial for the real-time remote lecture. It also introduces our ongoing plan to further develop this system. © Springer-Verlag Berlin Heidelberg 2002.

关键词： image communication systems

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A scalable and reliable hybrid scheme for image multicast applications

A scalable and reliable hybrid scheme for image multicast ap...

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European Signal processing conference (EUSIPCO)

作者： Abed Elhamid Lawabni Ahmed H. Tewfik Department of Electrical and Computer Engineering University of Minnesota Minneapolis MN

In real-time multicast communication scalability, reliability, and feedback implosion are of paramount importance. In this work we have developed an efficient feedback-free, entirely receiver-driven, and reliable visual information delivery hybrid scheme (SIGMA-EC) for multicast applications over unreliable communication networks, that requires no per-receiver status at the sender. Efficient bandwidth utilization is achieved by transmitting the parity packets over separate multicast channels, which receivers dynamically join and leave, preventing unnecessary receiver processing overhead and storage requirements for those packets that have already received correctly, and giving rise to a tradeoff between bandwidth and quality. Our XOR-based scheme's encoding and decoding processing time is an order of magnitude faster than conventional RS-based loss recovery schemes. Furthermore, we obtain all these advantages using a remarkably simple structure, both conceptually as well as computationally.

关键词： image reconstruction Receivers Bandwidth image edge detection visualization Software reliability

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