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33rd IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Jung, Sung-Kyo Ragot, Stephane Lamblin, ClauDe Proust, Stephane France Telecom R&D TECH SSTP F-22307 Lannion France

ISBN: (纸本)9781424414833

This paper describes a 12.2-32 kbps scalable wideband speech and audio coder interoperable with GSM enhanced full-rate (EFR). This coder, referred to as EFR-EV, is designed using the ITU-T G.729.1 multi-stage coding structure. Specifically, EFR-EV consists of three stages: a code-excited linear prediction (CELP) stage derived from EFR, time-domain bandwidth extension (TDBWE), and time-domain aliasing cancellation (TDAC). In this paper, we show that the G.729.1 extension layers (i.e. TDBWE and TDAC) are quite generic for scalable codec design in the sense that they can be applied to EFR with limited adjustments. In addition, we propose a minor modification of the bit allocation procedure in TDAC stage, exploiting spectral masking only for higher frequency bands. The performance of EFR-EV and G.729.1 are evaluated in terms of objective/subjective quality, algorithmic delay, and complexity.

关键词： scalable wideband coder GSM EFR embedded coding EFR-EV G.729.1

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Hybrid Scheme for Lifting Based Image coding

Hybrid Scheme for Lifting Based Image Coding

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7th International Conference on Computer Engineering and Systems (ICCES)

作者： Abd-elhafiez, Walaa M. Mofaddel, Mahmoud. A. Sohag Univ Dept Math & Comp Sci Fac Sci Sohag 82524 Egypt

ISBN: (纸本)9781467329613

This paper describes an efficient lifting based hybrid image coding (LB-HIC) scheme. The proposed scheme is based on using the lifting transform (LT) in conjunction with the discrete cosine transform (DCT) to provide coding performance superior to the popular image coders. The proposed method uses combination of the DCT coding and the high performance of the set partitioning in hierarchical tree (SPIHT) coding. The subband image data in the lifting domain is modified based on the DCT and the object classification of the coefficient in the low-frequency image subband (LL). The modification process provides a new subband image data containing almost the same information of the original one but having smaller values of the lifting coefficients. Simulation results of the proposed method demonstrate that, with small addition in the computational complexity of the coding process, the peak signal-to-noise ration (PSNR) performance of the proposed algorithm is much higher that that of the SPIHT test coder and some of famous image coding techniques

关键词： Image Compression Image coding Lifting Transform embedded coding JPEG 2000 DCT SPIHT

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An Efficient Wavelet-Based Image Coder

An Efficient Wavelet-Based Image Coder

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3rd International Conference on Information and Communication Technologies

作者： Brahimi, Tahar Laouir, Farid Kechacha, N. Univ JIJEL Fac Engn Sci Dept Elect Engn Jijel Algeria

ISBN: (纸本)9781424417513

The embedded zero-tree wavelet (EZW) coding algorithm which was first introduced by Shapiro is a very effective technique for low bit-rate still image compression. In the current study, we propose a novel algorithm to improve the performance of EZW coding. To reduce the scanning and symbol redundancy of the existing EZW the proposed method is based on the use of six symbols instead of four. The purpose of this technique is to avoid the encoding of the children of each significant coefficient on the condition that it has no significant descendant. In addition, It is shown that this new technique is not only fast and computationally efficient, but also retains the property of embeddedness and obtains higher coding efficiency when compared with the conventional EZW.

关键词： lossy imag coding embedded coding wavelet transform zerotree coding

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Adaptive segmentation of wavelet transform coefficients for video compression

Adaptive segmentation of wavelet transform coefficients for ...

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Conference on Image and Video Communications and Processing 2000

作者： Wasilewski, P Lodz Tech Univ Inst Elect PL-90537 Lodz Poland

ISBN: (纸本)0819435929

This paper presents video compression algorithm suitable for inexpensive real-time hardware implementation. This algorithm utilizes Discrete Wavelet Transform (DWT) with the new Adaptive Spatial Segmentation Algorithm (ASSA). The algorithm was designed to obtain better or similar decompressed video quality in compare to H.263 recommendation and MPEG standard using lower computational effort, especially at high compression rates. The algorithm was optimized for hardware implementation in low-cost Field Programmable Gate Array (FPGA) devices. The luminance and chrominance components of every frame are encoded with 3-level Wavelet Transform with biorthogonal filters bank. The low frequency subimage is encoded with an ADPCM algorithm. For the high frequency subimages the new Adaptive Spatial Segmentation Algorithm is applied. It divides images into rectangular blocks that may overlap each other. The width and height of the blocks are set independently. There are two kinds of blocks: Low Variance Blocks (LVB) and High Variance Blocks (HVB). The positions of the blocks and the values of the WT coefficients belonging to the HVB are encoded with the modified zero-tree algorithms. LVB are encoded with the mean value. Obtained results show that presented algorithm gives similar or better quality of decompressed images in compare to H.263, even up to 5 dB in PSNR measure.

关键词： image compression image segmentation subband coding embedded coding

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Superwideband Extension of G.718 and G.729.1 Speech Codecs

Superwideband Extension of G.718 and G.729.1 Speech Codecs

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11th Annual Conference of the International-Speech-Communication-Association 2010

作者： Laaksonen, Lasse Tammi, Mikko Malenovsky, Vladimir Vaillancourt, Tommy Lee, Mi Suk Yamanashi, Tomofumi Oshikiri, Masahiro Lamblin, Claude Kovesi, Balazs Miao, Lei Zhang, Deming Gibbs, Jon Francois, Holly Nokia Finland VoiceAge Canada ETRI Korea Republic of Panasonic Corp. Japan France Telecom France Huawei Technologies China Motorola United Kingdom

ISBN: (纸本)9781617821233

This communication presents the recently standardized superwideband (SWB) extensions of ITU-T G.718 and G.729.1. These extensions were standardized as G.718 annex B and G.729.1 annex E. The SWB functionality is implemented using embedded scalable layers on top of the wideband (WB) core codecs, and it extends the bit rate of the codecs to 48 and 64 kbit/s for the G.718 and G.729.1, respectively. The main technology is a two-mode SWB coding method of the high frequencies. In addition, the G.729.1 SWB extension enhances the lower frequency range. The codec performance is illustrated with some listening test results extracted from the ITU-T Characterization phase.

关键词： speech coding audio coding embedded coding scalable coding superwideband bandwidth extension ITU

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Visual progressive coding

Visual progressive coding

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Meeting on Visual Communications and Image Processing

作者： Li, J Sharp Labs Amer Camas WA 98607 USA

ISBN: (纸本)0819431249

The embedded coder has an attractive feature that the coding bitstream can be truncated later at any point and still decoded a perceptible image. It is common in conventional coding to improve the subjective quality of the coded image through adjusting the quantization step size inversely proportional to a set of visual weights. However, such scheme will not be effective in the embedded coder as different viewing condition may be called for at different stages of embedding. In this paper, we propose the visual progressive coding (VIP), which uses the visual weights to determine the order of embedding, rather than to requantize the transform coefficients. VIP can change the weights halfway through redefining the order of embedding according to the active weights. With such "reordering by weight" strategy, it is feasible to adjust the visual weights flexibly during the embedding process, and improve the subjective appearance of the image over the entire bit rate.

关键词： image coding embedded coding scalability visual frequency weighting visual progression

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Modified set partitioning in hierarchical trees algorithm based on hierarchical subbands

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JOURNAL OF ELECTRONIC IMAGING 2015年第3期24卷 033004-033004页

作者： Ochoa Dominguez, Humberto de J. Vergara Villegas, Osslan O. Cruz Sanchez, Vianey G. Univ Autonoma Ciudad Juarez Signal Proc Grp Elect & Comp Engn Dept Ciudad Juarez 32310 Chihuahua Mexico

This paper introduces a modified set partitioning in hierarchical trees (SPIHT) algorithm that reduces the number of comparison operations and, consequently, the execution time needed to encode an image as compared to the SPIHT algorithm. The threshold of each independent subband is calculated after applying the discrete wavelet transform to the image. Scanning of the sets inside the subbands is determined by the magnitude of the thresholds that establishes a hierarchical scanning not only for the set of coefficients with larger magnitude, but also for the subbands. The algorithm uses the set partitioning technique to sort the transform coefficients. Results show that the modified SPIHT significantly reduces the number of operations and the execution time without sacrificing visual quality and the PSNR of the recovered image. (C) The Authors.

关键词： image coding transform coding image processing embedded coding set partitioning in hierarchical trees

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Fixed-Rate Compressed Floating-Point Arrays

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2014年第12期20卷 2674-2683页

作者： Lindstrom, Peter Lawrence Livermore Natl Lab Ctr Appl Sci Comp Livermore CA 94550 USA

Current compression schemes for floating-point data commonly take fixed-precision values and compress them to a variable-length bit stream, complicating memory management and random access. We present a fixed-rate, near-lossless compression scheme that maps small blocks of 4(d) values in d dimensions to a fixed, user-specified number of bits per block, thereby allowing read and write random access to compressed floating-point data at block granularity. Our approach is inspired by fixed-rate texture compression methods widely adopted in graphics hardware, but has been tailored to the high dynamic range and precision demands of scientific applications. Our compressor is based on a new, lifted, orthogonal block transform and embedded coding, allowing each per-block bit stream to be truncated at any point if desired, thus facilitating bit rate selection using a single compression scheme. To avoid compression or decompression upon every data access, we employ a software write-back cache of uncompressed blocks. Our compressor has been designed with computational simplicity and speed in mind to allow for the possibility of a hardware implementation, and uses only a small number of fixed-point arithmetic operations per compressed value. We demonstrate the viability and benefits of lossy compression in several applications, including visualization, quantitative data analysis, and numerical simulation.

关键词： Data compression floating-point arrays orthogonal block transform embedded coding

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Trends and perspectives in image and video coding

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PROCEEDINGS OF THE IEEE 2005年第1期93卷 6-17页

作者： Sikora, T Tech Univ Berlin D-10587 Berlin Germany

The objective of the paper is to provide an overview on recent trends and future perspectives in image and video coding. Here, I review and the rapid development in the field during the past 40 years and outline current state-of-the art strategies for coding images and videos. These and other coding algorithms are discussed in the context of international JPEG, JPEG 2000, MPEG-1/2/4, and H.261/3/4 standards. Novel techniques targeted at achieving higher compression gains, error robustness, and network/device adapt-ability are described and discussed.

关键词： discrete cosine transform (DCT) distributed source coding embedded coding error concealment image coding International Telecommunication Union-Telecommunications (ITU-T) Joint Photographic Experts Group (JPEG) motion compensation JPEG 2000 Motion Picture Experts Group (MPEG) standardization video coding wavelets

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Context-modeled wavelet difference reduction coding based on fractional bit-plane partitioning

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IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS 2004年第2期E87D卷 491-493页

作者： Yuan, YF Mandal, MK Univ Alberta Dept Elect & Comp Engn Edmonton AB T6G 2V4 Canada

A simple and efficient context modeling technique (CM-WDR) is proposed to improve the performance of the wavelet difference reduction (WDR) algorithm for image compression. The CM-WDR employs an adaptive scanning orde... 详细信息

关键词： Context modeling embedded coding Image compression Wavelet

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