Point cloud compression (PCC) has been rapidly evolving in the context of international standards. Despite the inherent scalability of octree-based geometry descriptions, current attribute compression techniques preve...
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Point cloud compression (PCC) has been rapidly evolving in the context of international standards. Despite the inherent scalability of octree-based geometry descriptions, current attribute compression techniques prevent full scalability of compressed point clouds. We propose an improvement on an embedded attribute encoding method for point clouds based on set partitioning in hierarchical trees (SPIHT). We propose to use a multi-layer perceptron (MLP) to model contexts in order to further compress the final bit-stream. The encoder is used along with the region-adaptive hierarchical transform, which has been a popular transform for point cloud coding and is included in the standard geometry-based point cloud coder (G-PCC). The result is an encoder that is efficient, scalable, and, best of all, embedded. That is, higher compression is achieved by further trimming the single bit-stream. Experimental results show approximately 13% BD-Rate reduction using MLP-based context modeling.
Many modern wavelet quantization schemes specify wavelet coefficient step sizes as continuous functions of an input step-size selection criterion;rate control is achieved by selecting an appropriate set of step sizes....
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Many modern wavelet quantization schemes specify wavelet coefficient step sizes as continuous functions of an input step-size selection criterion;rate control is achieved by selecting an appropriate set of step sizes. In embedded wavelet coders, however, rate control is achieved simply by truncating the coded bit stream at the desired rate. The order in which wavelet data are coded implicitly controls quantization step sizes applied to create the reconstructed image. Since these step sizes are effectively discontinuous, piece wise-constant functions of rate, this paper examines the problem of designing a coding order for such a coder, guided by a quantization scheme where step sizes evolve continuously with rate. In particular, it formulates an optimization problem that minimizes the average relative difference between the piecewise-constant implicit step sizes associated with a layered coding strategy and the smooth step sizes given by a quantization scheme. The solution to this problem implies a coding order. Elegant, near-optimal solutions are presented to optimize step sizes over a variety of regions of rates, either continuous or discrete. This method can be used to create layers of coded data using any scalar quantization scheme combined with any wavelet bit-plane coder. It is illustrated using a variety of state-of-the-art coders and quantization schemes. In addition, the proposed method is verified with objective and subjective testing.
Summary form only given. Most existing image coding techniques resolve the uncertainty of an image source on a pixel-by-pixel basis. We demonstrate the effectiveness of region-based image models for the class of palet...
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ISBN:
(纸本)0769514774
Summary form only given. Most existing image coding techniques resolve the uncertainty of an image source on a pixel-by-pixel basis. We demonstrate the effectiveness of region-based image models for the class of palette images. We propose to represent the index map of a palette image by a collection of successively refined color regions, from which the original index map can be reconstructed without any error. Within the framework of region-based modeling, we present a conditional coding approach to avoid information leakage during the multiple passes. Motivated by the distinguished characteristics of palette images, we propose to exploit topological property of isolated uniform-color regions while resolving the uncertainty of region boundaries. Our region-based image model not only provides an embedded representation of palette images in the topological space but also achieves excellent compression performance.
The visual information of a surveillance system should provide extended and just-in-time perception in monitored environments. However, delivering visual information of surveillance from nonstationary providers, such ...
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The visual information of a surveillance system should provide extended and just-in-time perception in monitored environments. However, delivering visual information of surveillance from nonstationary providers, such as mobile cameras, to designated end-users over bandwidth-limited networks is a challenging task. In this paper, for transmitting visual objects of interest, an embedded spatial coding approach is proposed to progressively encode the presentation quality of visual objects under receivers' bandwidth limitation. First, different levels of importance for the objects of interest are characterized by the standard edge detection algorithm and several designated priorities for these objects are progressively assigned. The spatial coding approach then adopts a wavelet-based image coding algorithm based on the assigned priority of each object of interest. Therefore, each individual receiver can adaptively obtain the best visual information of the most important object under its available bandwidth. The proposed priority assignment and spatial coding mechanism has been extensively tested and analyzed. The experimental results show that, under different bandwidth scenarios and required acceptable signal-quality levels, the end-users can obtain the best visual quality of the important objects of interest. Therefore, the importance of the objects of interest in real-time surveillance video can be properly determined and the required transmission quantity can be effectively allocated.
An embedded coding scheme for dense motion (optical flow) fields is proposed. Such a scheme is particularly useful in scalable video compression where one must compensate for inter-frame motion at various visual quali...
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ISBN:
(纸本)9781479958962
An embedded coding scheme for dense motion (optical flow) fields is proposed. Such a scheme is particularly useful in scalable video compression where one must compensate for inter-frame motion at various visual qualities and resolutions. However, the high cost of coding such fields has often made this option prohibitive. Using our previously developed 'breakpoint'-adaptive wavelet transform, we show that it is possible to code dense motion fields efficiently while simultaneously endowing the coded motion representation with embedded resolution and quality scalability attributes. Performance comparisons with the traditional non-scalable block-based model are also made and presented with the aid of a modified H.264/AVC JM reference encoder.
Recently, embedded coder of stereo image has attracted a lot of attentions not only because of limit transmission bandwidth but human visual system can perceive a sharp 3D image even when one of the images is coded as...
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ISBN:
(纸本)0780386477
Recently, embedded coder of stereo image has attracted a lot of attentions not only because of limit transmission bandwidth but human visual system can perceive a sharp 3D image even when one of the images is coded as a lower quality image. In this paper, we propose a novel DCT-based embedded stereo coder. Firstly, an adaptive Delaunay Triangulation (DT) mesh-based disparity estimation (DE) algorithm is used for obtaining disparity vectors. Then, we utilize Markov Random Field (MRF) model to further optimize disparity vectors, which results in more smooth disparity field. Moreover, an improved DCT-based bit-plane coder providing embedded bit stream is made use of encoding residual image. Different from conventional VLC-table bit-plane coding algorithm, this algorithm imposes context-based arithmetic coding algorithm, whose context models are specially designed by studying the characteristics of bit planes. Proven by experimental results, our coder outperforms traditional stereo coders 0.2-1.8dB. Meanwhile, it can provide embedded bit streams for adapting to channel bandwidth.
Traditional EBCOT algorithm encodes an image with the same block-based coding strategy and it is difficult to acquire perceptually consistent results. This paper presents an improved object-based embedded coding algor...
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ISBN:
(纸本)9781424437092
Traditional EBCOT algorithm encodes an image with the same block-based coding strategy and it is difficult to acquire perceptually consistent results. This paper presents an improved object-based embedded coding algorithm to enhance the flexibility and coding efficiency of the original EBCOT algorithm. The original image is segmented into objects and each object can be encoded independently with different strategy according to its visual interest. At the decoder, each object can be reconstructed progressively depend on the given bit-rate. As a whole, the improved algorithm is more flexible and may enhance the overall subjective image quality. Experiments are conducted and the results show that the proposed algorithm is effective.
Today's scientific simulations are confronting seriously limited I/O bandwidth, network bandwidth, and storage capacity because of immense volumes of data generated in high-performance computing systems. Data comp...
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ISBN:
(纸本)9798350337662
Today's scientific simulations are confronting seriously limited I/O bandwidth, network bandwidth, and storage capacity because of immense volumes of data generated in high-performance computing systems. Data compression has emerged as one of the most effective approaches to resolve the issue of the exponential increase of scientific data. However, existing state-of-the-art compressors also are confronting the issue of low throughput, especially under the trend of growing disparities between the compute and I/O rates. Among them, embedded coding is widely applied, which contributes to the dominant running time for the corresponding compressors. In this work, we propose a new kind of embedded coding algorithm, and apply it as the backend embedded coding of ZFP, one of the most successful lossy compressors. Our embedded coding algorithm uses bit groups instead of bit planes to store the compressed data, avoiding the time overhead of generating bit planes and group tests of bit planes, which significantly reduces the running time of ZFP. Our embedded coding algorithm can also accelerate the decompression of ZFP, because the costly procedures of the reverse of group tests and reconstructing bit planes are also avoided. Moreover, we provide theoretical proof that the proposed coding algorithm has the same compression ratio as the baseline ZFP. Experiments with four representative real-world scientific simulation datasets show that the compression and decompression throughput of our solution is up to 2.5x (2.1x on average), and up to 2.1x (1.5x on average) as those of ZFP, respectively.
This paper presents bandwidth-efficient speech transmission systems using rate-compatible channel coders and variable bitrate embedded source coders. Rate-compatible punctured convolutional codes (RCPC) are often used...
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This paper presents bandwidth-efficient speech transmission systems using rate-compatible channel coders and variable bitrate embedded source coders. Rate-compatible punctured convolutional codes (RCPC) are often used to provide unequal error protection (UEP) via progressive bit puncturing. RCPC codes are well suited for constellations for which Euclidean and Hamming distances are equivalent (BPSK and 4-PSK). This paper introduces rate-compatible punctured trellis codes (RCPT) where rate compatibility and UEP are provided via progressive puncturing of symbols in a trellis. RCPT codes constitute a special class of codes designed to maximize residual Euclidean distances (RED) after symbol puncturing. They can be designed for any constellation, allowing for higher throughput than when restricted to using 4-PSK. We apply RCPC and RCPT to two embedded source coders: a perceptual subband coder and the ITU embedded ADPCM G.727 standard. Different operating modes with distinct source/channel bit allocation and UEP are defined. Each mode is optimal for a certain range of AWGN channel SNRs. Performance results using an 8-PSK constellation clearly illustrate the wide range of channel conditions at which the adaptive scheme using RCPT can operate. For an 8-PSK constellation, RCPT codes are compared to RCPC with bit interleaved coded modulation codes (RCPC-BICM). We also compare performance to RCPC codes used with a 4-PSK constellation.
One of the major applications of wireless sensors networks (WSNs) is vibration measurement for the purpose of structural health monitoring and machinery fault diagnosis. WSNs have many advantages over the wired networ...
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One of the major applications of wireless sensors networks (WSNs) is vibration measurement for the purpose of structural health monitoring and machinery fault diagnosis. WSNs have many advantages over the wired networks such as low cost and reduced setup time. However, the useful bandwidth is limited, as compared to wired networks, resulting in relatively low sampling. One solution to this problem is data compression which, in addition to enhancing sampling rate, saves valuable power of the wireless nodes. In this work, a data compression scheme, based on Modified Discrete Cosine Transform (MDCT) followed by embedded Harmonic Components coding (EHCC) is proposed to compress vibration signals. The EHCC is applied to exploit harmonic redundancy present is most vibration signals resulting in improved compression ratio. This scheme is made suitable for the tiny hardware of wireless nodes and it is proved to be fast and effective. The efficiency of the proposed scheme is investigated by conducting several experimental tests. (C) 2014 ISA. Published by Elsevier Ltd. All rights reserved.
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