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International Conference on Computer Engineering and Technology, ICCET

作者： Guosheng Gu Yinwei Zhan Faculty of Computer Guangdong University of Technology Guangzhou China

This paper presents an image coding technique based on contourlet transform. The redundancy of the contourlet transform is eliminated by switching the LP decomposition step to separable wavelet transform. The transform is then optimized through a wavelet coefficient weighting process in order to enhance the visual quality in the image domain, and with that the directional filter bank(DFB) are employed to high frequency wavelet subbands. At last, all the resulted subbands are efficiently coded with EBCOT. At the same bit rates, a gain of up to 0.3~0.6 dB over JPEG2000 has been observed for standard images with directional features.

关键词： Image coding Frequency Wavelet transforms Discrete transforms Filter bank Discrete wavelet transforms Laplace equations Bit rate Paper technology transform coding

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Rate-distortion optimal wavelet packet transform for low bit rate video coding

Rate-distortion optimal wavelet packet transform for low bit...

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IEEE International Workshop on Imaging Systems and Techniques (IST)

作者： Xiaofei Zong Aidong Men Bo Yang School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing China

In this paper, we introduce a new implementation of motion-compensated temporal filter (MCTF) based video coder which utilizes rate-distortion optimal wavelet packet transform (RDWP) for some low bit rate video coding application scenarios. Although enhanced MC-EZBC video coder provides good scalability and high coding efficiency at high bit rates, reconstructed video quality will drop rapidly with increased motion at low bit rates. The proposed video coder applies optimal wavelet packet transform to each temporal frame and rate-distortion optimization to each GOP. Experimental results show this codec provides better performance than MC-EZBC with PSNR improved 0.3-1.2dB at low bit rates.

关键词： Rate-distortion Wavelet packets Wavelet transforms Bit rate Video coding Image coding Filters Video compression Entropy transform coding

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Image coding using Periodic Walsh Piecewise-Linear transform

Image coding using Periodic Walsh Piecewise-Linear transform

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IEEE International Conference on Multimedia Computing and Systems (ICMCS)

作者： Fituri H. Belgassem Communications Engineering Department Higher Institute of Electronics Bani Walid Libya

The analysis of image coding using Periodic Walsh Piecewise-Linear (PWL) transform will be presented in this paper. The coding method employs an integer bit allocation scheme and Llyod-Max quantizers. Experimental results have shown that best results are obtained by modeling the DC coefficient using a one-sided Gaussian distribution and the AC coefficients by using a Laplacian distribution. Comparison of coding real images using the periodic Walsh piecewise-linear transform and some orthogonal transforms will be given. Computer simulation results indicate that the image coding efficiency of the periodic Walsh piecewise-linear transform is close to that of Walsh and Haar transforms from the PSNR viewpoint.

关键词： Image coding Piecewise linear techniques Bit rate transform coding Pixel PSNR Image processing Compaction Image storage Data compression

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LOW-COMPLEXITY BANDWIDTH EXTENSION IN MDCT DOMAIN FOR LOW-BITRATE SPEECH coding

LOW-COMPLEXITY BANDWIDTH EXTENSION IN MDCT DOMAIN FOR LOW-BI...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Tsujino, Kosuke Kikuiri, Kei Research Laboratories NTT DOCOMO Inc. Japan

ISBN: (纸本)9781424423538

We propose a low-complexity Bandwidth Extension (BWE) method operating in the Modified Discrete Cosine transform (MDCT) domain to reduce the bitrate of wideband and super-wideband speech codecs. The proposed method generates a high-frequency signal by copying the MDCT spectrum from the low frequency part, and then adjusts tonality to improve the subjective quality of the generated high-frequency signal. In combination with an MDCT-based transform codec, it requires only 64.9% of the computational complexity of MPEG-4 Spectral Band Replication (SBR). It also achieves subjective quality better than SBR for many speech samples.

关键词： transform coding Speech coding Speech communication

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SEEING IS NOT BELIEVING

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IEEE SPECTRUM 2009年第8期46卷 44-+页

作者： Farid, Hany Dartmouth Coll Hanover NH 03755 USA

Altering digital imagery is now ubiquitous. People have come to expect it in the fashion and entertainment world, where airbrushing blemishes and wrinkles away is routine. And anyone surfing the Web is routinely subjected to crude photographic mashups like the Palin hoax, whose creators clearly aren't interested in realism but in whatever titillation or outrage they can generate. Even as experts continue to develop techniques for exposing photographic frauds, new techniques for creating better and harder-to-detect fakes are also evolving. As in the battle against spam and computer viruses, it seems inevitable that the arms race between the forger and the forensic analyst will continue to escalate, with no clear victor. Improved image forensics will never be able to eradicate or prevent digital tampering, but these techniques can make it more time-consuming and difficult for forgers to ply their trade. Tomorrow's technology will almost certainly enable digital manipulations that today seem unimaginable, and the science of digital forensics will have to work hard to keep pace. It is my hope that these new techniques, along with a greater awareness of the technological possibilities and sensible updates in policy and law, will help the media, the courts, and the public contend with the exciting but often baffling events of our digital age.

关键词： Pixel Image coding transform coding Charge coupled devices Image color analysis Data mining Cameras

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Infinity-Norm Rotation transforms

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2009年第7期57卷 2594-2603页

作者： Yang, Lei Hao, Pengwei Peking Univ Ctr Informat Sci Beijing 100871 Peoples R China Univ London Dept Comp Sci London E1 4NS England

A new general paradigm of dynamic-range-preserving one-to-one mapping-infinity-norm rotations, analogous to the general 2-norm rotations, are proposed in this paper. Analogous to the well-known discrete cosine transforms, the linear 2-norm rotation transforms which preserve the 2-norm of the rotated vectors, the proposed infinity-norm rotation transforms are piecewise linear transforms which preserve the infinity-norm of vectors. Besides the advantages of perfect reversibility, in-place calculation and dynamic range preservation, the infinity-norm rotation transforms also have good energy-compact ability, which is suitable for signal compression and analysis. It can be implemented by shear transforms based on the 2-D rotation factorization of similar orthogonal transform matrices, such as DCT matrices. The performance of the new transforms is illustrated with 2-D patterns and histograms. Its good performance in lossy and lossless image compression, compared with other integer reversible transforms, is demonstrated in the experiments.

关键词： Discrete cosine transform dynamic range infinity-norm rotation integer reversible transform transform coding

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Simple lossless preprocessing algorithms for text compression

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IET SOFTWARE 2009年第1期3卷 37-45页

作者： Robert, L. Nadarajan, R. Govt Arts Coll Dept Comp Sci Coimbatore Tamil Nadu India PSG Coll Technol Dept Comp Applicat Coimbatore Tamil Nadu India

Lossless data compression researchers have developed highly sophisticated approaches, such as Huffman encoding, arithmetic coding, the Lempel-Ziv family, prediction by partial matching and Burrow-Wheeler transform based algorithms. One approach for attaining better compression is to develop generic, reversible transformation that can be applied to a source text that improves an existing compression algorithm's ability to compress. A few reversible transformation techniques that give better compression ratios are presented. A method, which transforms a text file into intermediate file with minimum possible byte values, is proposed. An attempt has been made to reduce the number of possible bytes that appear after every byte in the source file. This increases backend algorithm's compression performance.

关键词： lossless data compression Lempel-Ziv family text compression data compression arithmetic coding arithmetic codes transform coding Huffman codes lossless preprocessing algorithms text analysis Burrow-Wheeler transform Document processing techniques Huffman encoding

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Octahedral transforms for 3-D Image Processing

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IEEE TRANSACTIONS ON IMAGE PROCESSING 2009年第12期18卷 2618-2628页

作者： Lenz, Reiner Latorre Carmona, Pedro Linkoping Univ Dept Sci & Technol SE-60174 Norrkoping Sweden Dept Lenguajes & Sistemas Informat Castellon De La Plana 12071 Spain

The octahedral group is one of the finite subgroups of the rotation group in 3-D Euclidean space and a symmetry group of the cubic grid. Compression and filtering of 3-D volumes are given as application examples of its representation theory. We give an overview over the finite subgroups of the 3-D rotation group and their classification. We summarize properties of the octahedral group and basic results from its representation theory. Wide-sense stationary processes are processes with group theoretical symmetries whose principal components are closely related to the representation theory of their symmetry group. Linear filter systems are defined as projection operators and symmetry-based filter systems are generalizations of the Fourier transforms. The algorithms are implemented in Maple/Matlab functions and worksheets. In the experimental part, we use two publicly available MRI volumes. It is shown that the assumption of wide-sense stationarity is realistic and the true principal components of the correlation matrix are very well approximated by the group theoretically predicted structure. We illustrate the nature of the different types of filter systems, their invariance and transformation properties. Finally, we show how thresholding in the transform domain can be used in 3-D signal processing.

关键词： Compression filter design Fourier transform group presentation octahedral group 3-D image processing transform coding

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JHelioviewer: Visualizing Large Sets of Solar Images Using JPEG 2000

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COMPUTING IN SCIENCE & ENGINEERING 2009年第5期11卷 38-47页

作者： Mueller, Daniel Fleck, Bernhard Dimitoglou, George Caplins, Benjamin W. Amadigwe, Desmond E. Garcia Ortiz, Juan Pablo Wamsler, Benjamin Alexanderian, Alen Hughitt, V. Keith Ireland, Jack European Space Agcy F-75738 Paris 15 France Hood Coll Frederick MD USA Univ Almeria Supercomp Algorithms Res Grp Comp Architecture Dept Almeria Spain Univ Appl Sci Ulm Germany Univ Maryland Baltimore Cty Baltimore MD 21228 USA Univ Almeria Supercomp Algorithms Res Grp Dept Elect Almeria Spain

All disciplines that work with image data-from astrophysics to medical research and historic preservation-increasingly require efficient ways to browse and inspect large sets of high-resolution images. Based on the JPEG 2000 image-compression standard, the JHelioviewer solar image visualization tool lets users browse petabyte-scole image archives as well as locate and manipulate specific data sets.

关键词： Image Resolution Data Visualization Image Storage Observatories Motion Pictures Image coding Sun transform coding Data Visualization

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On the Uniform Quantization of a Class of Sparse Sources

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IEEE TRANSACTIONS ON INFORMATION THEORY 2009年第7期55卷 3243-3263页

作者： Fraysse, Aurelia Pesquet-Popescu, Beatrice Pesquet, Jean-Christophe Univ Paris Sud CNRS Signaux & Syst Lab F-91192 Gif Sur Yvette France Telecom ParisTech Signal & Image Proc Dept F-75634 Paris 13 France Univ Paris Est Inst Gaspard Monge F-77454 Marne La Vallee 2 France Univ Paris Est CNRS UMR 8049 F-77454 Marne La Vallee 2 France

We consider the uniform scalar quantization of a class of mixed distributed memoryless sources, namely sources having a Bernoulli Generalized Gaussian (BGG) distribution. Both for low and high resolutions, asymptotic expressions of the distortion for a pth-order moment error measure, and close approximations of the entropy are provided for these sources. Operational rate-distortion functions at high bit rate and their slope factors at low bit rate are derived. The dependence of these results on p and the distribution parameters as well as the relation to the Shannon optimal rate-distortion bound are then discussed. The application of these results to transform coding in two simple cases is finally highlighted.

关键词： Asymptotic performance Bernoulli-Gaussian model generalized Gaussian mixed distribution rate-distortion function sparsity transform coding uniform quantization

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