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Conference on Applications of Digital Image Processing XXIII

作者： Wu, GK Gormish, MJ Boliek, M Ricoh Silicon Valley Inc Menlo Park CA 94025 USA

ISBN: (纸本)0819437603

The JPEG2000 still image compression standard has adopted a new compression paradigm: "Encode once, decode many." JPEG2000 architecture allows the codestream to be decoded differently for different application needs. The codestream can be decoded to produce lossless and lossy images, specific spatial regions of the image or images with different quality and resolution. The syntax contains pointers and length fields which allow relevant coded data to be identified without the entropy coder or transforms. Consequently, the codestream can be "parsed" to create different codestreams without transcoding. For example, such parsing operation can create a new codestream which contains a lower resolution image (e.g. thumbnail) of the original codestream. If a codestream is produced appropriately, it can also be converted to codestreams of lower quality images, or images containing only a specific spatial region. This feature is very useful for many applications, especially on the internet.

关键词： JPEG2000 wavelet transform syntax marker embedded coding parser region of interest image compression standard ITU-T Rec. T.800 l IS 15544-1:2000

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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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An embedded still image coder with rate-distortion optimization

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IEEE TRANSACTIONS ON IMAGE PROCESSING 1999年第7期8卷 913-924页

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

It is well known that the fixed rate coder achieves optimality when all coefficients are coded with the same rate-distortion (R-D) slope. In this paper, we show that the performance of the embedded coder can be optimized in a rate-distortion sense by coding the coefficients with decreasing R-D slope. We denote such coding strategy as rate-distortion optimized embedding (RDE). RDE allocates the available coding bits first to the coefficient with the steepest R-D slope, i.e., the largest distortion decrease per coding bit. The resultant coding bitstream can be truncated at any point and still maintain an optimal R-D performance. To avoid the overhead of coding order transmission, we use the expected R-D slope, which can be calculated from the coded bits and is available in both the encoder and the decoder. With the probability estimation table of the QM-coder, the calculation of the R-D slope can be just a lookup table operation. Experimental results show that the rate-distortion optimization significantly improves the coding efficiency in a wide bit rate range.

关键词： embedded coding image coding rate-distortion optimization rate-distortion slope scalability wavelet

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An embedded DCT-based still image coding algorithm

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IEEE SIGNAL PROCESSING LETTERS 1998年第6期5卷 135-137页

作者： Nister, D Christopoulos, C Ericsson Telecom AB Compress Lab S-12625 Stockholm Sweden

In this letter, an embedded discrete cosine transform-based (DCT-based) image coding algorithm is described. The algorithm outperforms other DCT-based coders published in the literature, including the Joint Photograph... 详细信息

关键词： discrete cosine transform embedded coding JPEG

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Multiresolutional encoding/decoding in embedded image and video coders 6

Multiresolutional encoding/decoding in embedded image and vi...

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Hybrid Image and Signal Processing VI

作者： Xiong, ZX Kim, BJ Pearlman, WA Univ Hawaii Dept Elect Engn Honolulu HI 96822 USA

ISBN: (纸本)0819428388

We address multiresolutional encoding and decoding within the embedded zerotree wavelet (EZW) framework for both images and video. By varying a resolution parameter, one can obtain decoded images at different resolutions from one single encoded bitstream, which is already rate scalable for EZW coders. Similarly one can decode video sequences at different rates and different spatial and temporal resolutions from one bitstream. Furthermore, a layered bitstream can be generated with multiresolutional encoding, from which the higher resolution layers can be used to increase the spatial/temporal resolution of the images/video obtained from the low resolution layer. In other words, we have achieved full scalability in rate and partial scalability in space and time. This added spatial/temporal scalability is significant for emerging multimedia applications such as fast decoding, image/video database browsing, telemedicine, multipoint video conferencing, and distance learning.

关键词： multiresolutional coding wavelets embedded coding scalability

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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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Rate control for an embedded wavelet video coder

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 1997年第4期7卷 696-702页

作者： Cheng, PY Li, J Kuo, CCJ SHARP LABS AMER DIGITAL VIDEO DIV CAMAS WA 98607 USA UNIV SO CALIF INTEGRATED MEDIA SYST CTR LOS ANGELES CA 90089 USA UNIV SO CALIF DEPT ELECT ENGN SYST LOS ANGELES CA 90089 USA

embedded coders provide a better rate-distortion tradeoff while the coded bit stream can be truncated at any point without a significant perceptible distortion. In this work, we investigate rate control for an embedded wavelet video coder bg converting the rate control problem to a bit allocation problem for each frame. Then, a computationally efficient rate control algorithm is derived by exploiting the rate distortion performance of the embedded wavelet coder and the frame dependency between the reference frame and the predictive frame, Experiments are performed to demonstrate the superior performance of the embedded wavelet video coder with the proposed rate control scheme. It is shown that the proposed rate control strategy outperforms the fixed allocation rate control by 0.1-0.4 dB for a variety of sequences, and the performance gain can be as large as 1.3-2.7 dB around scene changes.

关键词： embedded coding MPEG multimedia rate control video coding video compression wavelet transform

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A perceptually based embedded subband speech coder

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IEEE TRANSACTIONS ON SPEECH AND AUDIO PROCESSING 1997年第2期5卷 131-140页

作者： Tang, B Shen, A Alwan, A Pottie, G INTEL CORP HILLSBOROOR 97124 UNIV CALIF LOS ANGELES DEPT ELECT ENGNLOS ANGELESCA 90095

A new scheme for robust, high-quality, embedded speech coding based on subband decomposition and perceptually optimized bit allocation and prioritization is presented, An infinite impulse response (IIR) quadrature mirror filterbank (QMF) performs subband decomposition, A perceptual model, computed using subband spectral analysis, optimizes the coder's perceptual quality, Dynamic bit allocation and prioritization is combined with embedded quantization resulting in little performance degradation relative to a nonembedded implementation, The coder output is scalable from high quality at higher bit rates to lower quality at lower bit rates, supporting a wide range of service and resource utilization, The lower bit-rate representation is obtained simply through truncation of the higher bit-rate representation, Since source-rate adaptation is performed through truncation of the encoded stream, interaction with the coder is not required, making the embedded coder ideally suited for rate-adaptive communication systems, performance for both speech and music was verified through subjective listening tests.

关键词： speech coding subband coding embedded coding perceptual metrics

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An embedded still image coder with rate-distortion optimization

An embedded still image coder with rate-distortion optimizat...

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Visual Communications and Image Processing 1998 Conference

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

ISBN: (纸本)0819427497

It is well known that the fixed rate coder achieves optimality when all coefficients are coded with the same rate-distortion (R-D) slope. In this paper, we show that the performance of the embedded coder can be optimized in a rate-distortion sense by coding the coefficients with decreasing R-D slope, We denote such coding strategy as rate-distortion optimized embedding (RDE). RDE allocates the available coding bits first to the coefficient with the steepest R-D slope, i.e. the largest distortion decrease per coding bit. The resultant coding bitstream can be truncated at any point and still maintain an optimal R-D performance. To avoid the overhead of coding Order transmission, we use the expected R-D slope which can be calculated from the coded bits and are available in both the encoder and the decoder. With the probability estimation table of the QM-coder, the calculation of the R-D slope can be just a lookup table operation. Experimental results show that the rate-distortion optimization significantly improves the coding efficiency in a wide range of coding rates.

关键词： image coding embedded coding rate-distortion slope rate-distortion optimization scalability wavelet

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embedded wavelet packet image coder with fast rate-distortion optimized decomposition

Embedded wavelet packet image coder with fast rate-distortio...

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1997 Conference on Visual Communications and Image Processing

作者： Li, J Kuo, CCJ Cheng, PY Univ. of Southern California (United States) Physical Optics Corp. (United States)

ISBN: (纸本)0819424358

A fast rate-distortion (R-D) optimized wavelet packet (WP) transform is proposed for image compression in this research. By analyzing the R-D performance of the quantizer and the entropy coder, we show that the coding distortion D can be modeled as an exponentially decaying function as the coding rate R increases. With this exponential R-D model, it is proved that the constant R-D slope criterion for optimum bit allocation is equivalent to the constant distortion criterion, which can be easily implemented via thresholding. Based on this analytical result, we develop a fast wavelet packet decomposition scheme which is optimized in the R-D sense by comparing simple parameters associated with each wavelet packet band such as the 1st or 2nd absolute moments. We have performed extensive experiments to demonstrate the performance of an image coder using the proposed R-D optimized wavelet packet transform, and shown that our scheme is highly competitive with all well known state-of-the-art image coders.

关键词： image compression rate-distortion wavelet packets wavelet coding embedded coding

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