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25th IEEE International Conference on Image Processing (ICIP)

作者： Limuti, Simone Polo, Enrico Milani, Simone Univ Padua Dept Informat Engn Padua Italy

ISBN: (纸本)9781479970612

With the advent of virtual and augmented reality applications, 3D and free-viewpoint representations have evolved towards solid scene models using meshes and point clouds. Recent works have been addressing point clouds compression via octree-based hierarchical strategies in order to enable a multi-resolution coding and visualization at a reasonable computational cost. This paper presents a voxelized dynamic point cloud coding scheme that combines a Cellular Automata block reversible transform for geometric data with a region adaptive transform for color data. Temporal redundancy is removed using a low-complexity prediction scheme to minimize the computational complexity and reduce the coded bit rate. Experimental results showed that the proposed solution obtained a significant bit rate reduction in lossless geometry coding and an improved rate-distortion performance in the lossy coding of color components with respect to state-of-the-art strategies.

关键词： dynamic point cloud compression cellular automata transform coding octree voxel color

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Closed-form quality measures for compressed medical images: Statistical preliminaries for transform coding

Closed-form quality measures for compressed medical images: ...

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25th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society

作者： Li, DL Loew, M George Washington Univ Dept Elect & Comp Engn Washington DC 20037 USA

ISBN: (纸本)0780377893

As digital imaging technology advances, the amount of image data we generate increases and the need for compressed images becomes apparent. Because lossy compression will yield higher compression ratios than lossless methods, objective assessment metrics of reconstructed image quality are needed. In medical applications, model observers, especially the channelized Hotelling observer, have been successfully used to predict human observer performance and to evaluate image quality for detection tasks on various backgrounds. To use model observers, however, requires knowledge of noise statistics. This paper finds closed-form expressions for the noise induced by transform coding, one of the most commonly used methods for image compression. Knowledge of the noise enables us to study the effect of image compression on the clinical utility of medical images that have been reconstructed after being compressed using transform coding. In this paper, by analyzing image compression procedures, we propose a block-based transform coding representation in 1-D form, identify the quantization noise as the sole distortion source in transform coding, and derive the compression noise statistics. We show that the probability density function (pdf) of the compression noise is defined as a function of the transform matrix and its corresponding quantization matrix in the transform coding algorithm. We prove that the compression noise is a normal distribution when the dimension of the transform (the block size) is typical. We also provide the pdf of JPEG compression noise as a function of the quantization table and the DCT transform bases. This work provides the theoretical foundation for using the model observers in closed mathematical form, and can be applied to other image compression application areas that require the statistics of compression noise as well.

关键词： transform coding model observers JPEG compression-induced noise

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Comparison of transform coding techniques for two-dimensional arbitrarily shaped images

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Multimedia Systems 1994年第6期1卷 231-239页

作者： Chang, Shih-Fu Messerschmitt, David G. Department of Electrical Engineering Columbia University New York 10027 NY United States Department of Electrical Engineering and Computer Sciences University of California at Berkeley Berkeley 94720 CA United States

Envisioned advanced multimedia video services include arbitrarily shaped (AS) image segments as well as regular rectangular images. Image segments of the TV weather report produced by the chromo-key technique [1] and image segments produced by video analysis and image segmentation [2-4] are typical examples of AS image segments. This paper explores efficient intraframe transform coding techniques for general two-dimensional (2D) AS image segments, treating the traditional rectangular images as a special case. In particular, we focus on the transform coding of the partially defined image blocks along the boundary of the AS image segments. We recognize two different approaches - the brute force transform coding approach and the shape-adaptive transform coding approach. The former fills the uncovered area with the optimal redundant data such that the resulting transform spectrum is compact. A simple but efficient mirror image extension technique is proposed. Once augmented into full image blocks, these boundary blocks can be processed by traditional block-based transform techniques like the popular discrete cosine transform (DCT). In the second approach, we change either the transform basis or the coefficient calculation process adaptively based on the shape of the AS image segment. We propose an efficient shape-projected problem formulation to reduce the dimension of the problem. Existing coding algorithms, such as the orthogonal transform by Gilge [5] and the iterative coding by Kaup and Aach [6], can be interpreted intuitively. We also propose a new adaptive transform based on the same principle as that used in deriving the DCT from the optimal Karhunen-Loeve transform (KLT). We analyze the tradeoff relationship between compression performance, computational complexity, and codec complexity for different coding schemes. Simulation results show that complicated algorithms (e.g., iterative, adaptive) can improve the quality by 5-10 dB at some computational or hardware

关键词： Arbitrarily-shaped image segments Object-oriented video coding Structured video transform coding

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RELIABLE SECRET-KEY BINDING FOR PHYSICAL UNCLONABLE FUNCTIONS WITH transform coding

RELIABLE SECRET-KEY BINDING FOR PHYSICAL UNCLONABLE FUNCTION...

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IEEE Global Conference on Signal and Information Processing (GlobalSIP)

作者： Gunlu, Onur Iscan, Onurcan Sidorenko, Vladimir Kramer, Gerhard Tech Univ Munich Arcisstr 21 D-80333 Munich Germany Huawei Technol Duesseldorf GmbH Riesstr 25 D-80992 Munich Germany

ISBN: (纸本)9781509045457

Different transforms are compared to extract bit sequences used in secret-key binding for highly-correlated physical-identifier outputs. A set of transforms that perform well in terms of decorrelation efficiency is applied to ring oscillator (RO) outputs to improve the reliability and uniqueness of the extracted sequence, information leakage to an eavesdropper about the secret key and RO outputs, secret-key length, and hardware cost. Low-complexity error-correction codes used in combination with the transform-coding algorithm and fuzzy commitment scheme are proposed for a realistic block-error probability constraint to illustrate a complete secrecy system that binds secret keys to noisy and correlated physical identifiers with better secret-key and privacy-leakage rates than existing methods.

关键词： Privacy reliability fuzzy commitment physical unclonable functions transform coding

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A Butterfly Structured Design of The Hybrid transform coding Scheme

A Butterfly Structured Design of The Hybrid Transform Coding...

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Picture coding Symposium (PCS)

作者： Han, Jingning Xu, Yaowu Mukherjee, Debargha Google Inc 1950 Charleston Rd Mountain View CA 94043 USA

ISBN: (纸本)9781479902941

The hybrid transform coding scheme that alternates amongst the asymmetric discrete sine transform (ADST) and the discrete cosine transform (DCT) depending on the boundary prediction conditions, is an efficient tool for video and image compression. It optimally exploits the statistical characteristics of prediction residual, thereby achieving significant coding performance gains over the conventional DCT-based approach. A practical concern lies in the intrinsic conflict between transform kernels of ADST and DCT, which prevents a butterfly structured implementation for parallel computing. Hence the hybrid transform coding scheme has to rely on matrix multiplication, which presents a speed-up barrier due to under-utilization of the hardware, especially for larger block sizes. In this work, we devise a novel ADST-like transform whose kernel is consistent with that of DCT, thereby enabling butterfly structured computation flow, while largely retaining the performance advantages of hybrid transform coding scheme in terms of compression efficiency. A prototype implementation of the proposed butterfly structured hybrid transform coding scheme is available in the VP9 codec repository.

关键词： transform coding discrete cosine transforms Butterfly DCT gene Structural design HYBRID Hybrid electric vehicles Matrix multiplication

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Reversible transform coding of images

Reversible transform coding of images

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Conference on Visual Communications and Image Processing 96

作者： Komatsu, K Sezaki, K UNIV TOKYO INST IND SCIMINATO KUTOKYO 106JAPAN

ISBN: (纸本)0819421030

Though reversible predictive coding and reversible subband coding exist already as reversible coding of gray-level still images, reversible method has almost not been proposed against transform coding. Therefore, in this paper, we propose some reversible transform coding methods. In case that we use conventional transform coding as it is, we have to make the number of levels of the transform coefficient very large in order to reconstruct the input signal with no distortion. Therefore, we propose transform codings that have reversibility whereas the number of levels of the transform coefficient are not very large. We propose reversible coding methods that correspond to the discrete Walsh-Hadamard, Haar, and cosine transform. Furthermore, we propose a method that uses the difference of the n-th order, a method of which the number of levels of the transform coefficient is the same as that of the input signal, and a reversible overlap transform coding method. Simulation shows that the compression efficiency of the proposed method is almost the same as that of predictive coding.

关键词： image coding reversible coding transform coding subband coding predictive coding

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GLOBAL AND LOCAL RATE-DISTORTION OPTIMIZATION FOR LAPPED BIORTHOGONAL transform coding

GLOBAL AND LOCAL RATE-DISTORTION OPTIMIZATION FOR LAPPED BIO...

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IEEE International Conference on Image Processing

作者： Winken, Martin Marpe, Detlev Wiegand, Thomas Fraunhofer HHI Image Proc Dept D-10587 Berlin Germany

ISBN: (纸本)9781424479948

It is a well-known fact that, in order to overcome annoying blocking artifacts, transforms with block-overlapping basis functions have been proposed for image coding. Typically in transform coding, the encoder determines the transform coefficient values by applying the forward transform followed by scalar quantization. In this paper we present an approach, how rate-distortion optimized Lapped Biorthogonal transform (LBT) coefficient values can be determined by solving l(1)-regularized least squares problems. We compare a global version, where all the transform coefficients are obtained in one single optimization step, and a local version, where the optimization is done separately for each block, which results in losing optimality, but achieving highly reduced complexity. Our simulation results show gains of about 0.5 dB PSNR compared to ordinary forward transform and scalar quantization with only small losses (< 0.1 dB) for the local variant.

关键词： Lapped transforms LBT transform coding Image coding

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Distributed MIMO Uplink Capacity under transform coding Fronthaul Compression

Distributed MIMO Uplink Capacity under Transform Coding Fron...

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IEEE International Conference on Communications (IEEE ICC)

作者： Wiffen, Fred Bocus, Mohammud Z. Doufexi, Angela Nix, Andrew Univ Bristol Commun Syst & Networks Res Grp Bristol Avon England Toshiba Res Europe Ltd Bristol Avon England

ISBN: (纸本)9781538680889

In this work we analyse the capacity of the distributed MIMO uplink when transform coding is applied locally at each remote radio head (RRH) to compress fronthaul traffic. Assuming the use of optimal scalar compression, we derive a closed form capacity expression for the distributed MIMO uplink under Gaussian signalling, which is shown to be a function of both local and global channel eigendecompositions. We then outline two rate allocation schemes for efficiently allocating the available fronthaul to the compressed scalars, based on either local or global channel state information (CSI). Numerical results under Rayleigh fading conditions are presented which show that transform coding can provide a significant compression gain relative to direct signal quantisation, which grows as the number of antennas deployed at each RRH increases. Results also show that allocating fronthaul based on global CSI significantly improves performance, especially as the number of RRHs deployed increases.

关键词： distributed MIMO fronthaul compression transform coding cell-free C-RAN

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Approximation algorithms for wavelet transform coding of data stream.

Approximation algorithms for wavelet transform coding of dat...

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17th ACM-SIAM Symposium on Discrete Algorithms

作者： Guha, Sudipto Harb, Boulos Univ Penn Dept Comp Informat Sci Philadelphia PA 19104 USA Google Inc New York NY 10011 USA

ISBN: (纸本)9780898716054

This paper addresses the problem of finding a B-term wavelet representation of a given discrete function f is an element of R-n whose distance from f is minimized. The problem is well understood when we seek to minimize the Euclidean distance between f and its representation. The first-known algorithms for finding provably approximate representations minimizing general f, distances (including l(infinity)) under a wide variety of compactly supported wavelet bases are presented in this paper. For the Haar basis, a polynomial time approximation scheme is demonstrated. These algorithms are applicable in the one-pass sublinear-space data stream model of computation. They generalize naturally to multiple dimensions and weighted norms. A universal representation that provides a provable approximation guarantee under all p-norms simultaneously;and the first approximation algorithms for bit-budget versions of the problem, known as adaptive quantization, are also presented. Further, it is shown that the algorithms presented here can be used to select a basis from a tree-structured dictionary of bases and find a B-term representation of the given function that provably approximates its best dictionary-basis representation.

关键词： adaptive quantization best basis selection compactly supported wavelets nonlinear approximation sparse representation streaming algorithms transform coding universal representation

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TIME-SCALE MODIFICATION OF AUDIO SIGNALS USING MULTI-RELATIVE ONSET TIME ESTIMATIONS IN SINUSOIDAL transform coding

TIME-SCALE MODIFICATION OF AUDIO SIGNALS USING MULTI-RELATIV...

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44th Asilomar Conference on Signals, Systems and Computers

作者： Kim, Jonathan Clements, Mark Georgia Inst Technol Ctr Signal & Image Proc Sch Elect & Comp Engn Atlanta GA 30332 USA

ISBN: (纸本)9781424497218

The traditional sinusoidal transform coder (STC) was originally developed for analysis, synthesis, and modification of speech and other non-polyphonic audio signals. In this paper, a novel method of time-scale modification for polyphonic and multi-pitch audio signals based on STC is proposed. The proposed method does not require a pitch estimation, and as such, it enables STC based algorithms to perform modifications on polyphonic audio signals. The frequency jitter artifacts in the traditional STC are mostly due to the inaccurate onset time estimates measured by pitch periods. The proposed method eliminates the frequency jitter artifacts significantly by using multi-onset time estimations. Technical Area: H. Speech, Image and Video Processing: 4. Narrowband/Wideband Speech and Audio coding

关键词： H. Speech Image and Video Processing: 4. Narrowband/Wideband Speech and Audio coding audio signals transform coding SINGLE STRIP CONTAINERS Pitch estimation time of onset Sinusoidal MODIFICATION pitch period

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