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About 4,742 papers for “entropy coding”

Entropy Coding

Iain E. Richardson · 2024

An entropy encoder converts a sequence of symbols or syntax elements into a bitstream, and an entropy decoder converts the bitstream back into a sequence of symbols. This chapter looks at where entropy coding sits in a video codec and what it achieves. High-efficiency video coding uses a combination of fixed-length coding, variable-length coding and BAC for different sections of the coded syntax. The chapter also looks at the main types of entropy coding used in video codecs, and arithmetic coding in detail. It presents the details of pre-processing. Pre-processing can help to minimise the information to be encoded, to maximise the efficiency of context-adaptive entropy coding and to improve computational performance. An entropy encoder can estimate or model the probability that symbol has a particular value. The chapter shows how entropy coding works in H.265/high-efficiency video coding and H.266/versatile video coding.

Cited by 1

Neural Coding and Entropy

Christof Koch · 1999

0.8> ffit (typically, ffit = 1 msec). This implies that we can characterize the entire response of the cell via a point process and only need to keep track of the times t i the impulses were generated. Typically, these times are written as series of delta function P i ffi(t \\Gamma t i ). In the following, we will abbreviate such a spike train as ft i g. Receptive fields and tuning curves then correspond to measuring the conditional probability P [ft i gj s(t)] : (1) The most complete description of the behavior of the neuron as a function of the stimulus is of course the joint probability distribution P [ft i g; s(t)] : (2) 1<F

Cited by 0

Lecture on Entropy Coding

Robert G. Maunder · EdShare Southampton (University of Southampton) · 2010

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Cited by 0Open access

Efficient Entropy Coding Method for Scalable Video Coding

Hyo-Min Choi, Jung-Hak Nam, Dong-Gyu Sim et al. · Journal of Broadcast Engineering · 2010

일반적으로 현재 사용되는 비디오 코덱들은 모두 시간적 공간적 특성을 적절히 고려하여 차분 신호를 엔트로피 부호화한다. 스케일러블 비디오 부호화(SVC, Scalable Video Coding)는 계층 간의 중복성을 제거하고자 새로운 3가지 예측 기술을 도입하였음에도 계층간 예측된 신호에는 여전히 이전의 엔트로피 부호화 방법을 그대로 사용하고 있다. 실험결과에 따르면 계층 간 예측 방법을 이용하여 취득한 차분신호는 기존의 시간적 공간적 예측 방법을 통하여 얻은 차분 신호와는 다른 특성을 갖고 있다. 본 논문에서는 계층 간 예측 기술을 통해 얻은 차분신호에 대하여 엔트로피 부호화시 해당 차분 신호가 갖는 특성이 적절히 고려된 엔트로피 부호화 방법을 제안한다. 계층 간 텍스쳐 예측을 통해 얻은 차분 신호를 엔트로피 부호화하기 위하여 부호화된 블록 패턴(Coded Block Pattern, CBP) 표를 재설계한다. 이에 대한 실험 결과는 새롭게 재설계된 CBP 표가 기존의 JSVM 9.18 대비 4CIF 해상도의 영상에 대해 평균 2.20%, CIF 해상도의 영상에 대해 평균 1.14% 의 BD-Bitrate가 감소된다. Generally existing video codec employs entropy coding to deal with residual signals with considering temporal and spatial properties. Scalable Video Coding(SVC) which is extension of H.264/AVC has three technical concepts for removing redundancies between inter-layers. In spite of using novel prediction method between inter-layers in SVC, it is still using same entropy coding method to residual signals. According to the studies, the residual obtained by inter-layer prediction technique has different features of residual signal acquired by spatial or temporal prediction technique. In this paper, we propose an efficient entropy coding method which codes the residual signal obtained by inter-layer prediction with regarding its features adequately. We re-designed the Coded Block Pattern(CBP) table suitably for inter-layer texture prediction. The experiments show that the proposed method can further reduce the BD-Bitrate up to average 2.20% in 4CIF and 1.14% in CIF resolution compared to the existing JSVM 9.18.

Cited by 1Open access

Faster Relative Entropy Coding with Greedy Rejection Coding

Gergely Flamich, Stratis Markou, Jose Miguel Hernandez Lobato · arXiv (Cornell University) · 2023

Relative entropy coding (REC) algorithms encode a sample from a target distribution $Q$ using a proposal distribution $P$ using as few bits as possible. Unlike entropy coding, REC does not assume discrete distributions or require quantisation. As such, it can be naturally integrated into communication pipelines such as learnt compression and differentially private federated learning. Unfortunately, despite their practical benefits, REC algorithms have not seen widespread application, due to their prohibitively slow runtimes or restrictive assumptions. In this paper, we make progress towards addressing these issues. We introduce Greedy Rejection Coding (GRC), which generalises the rejection based-algorithm of Harsha et al. (2007) to arbitrary probability spaces and partitioning schemes. We first show that GRC terminates almost surely and returns unbiased samples from $Q$, after which we focus on two of its variants: GRCS and GRCD. We show that for continuous $Q$ and $P$ over $\mathbb{R}$ with unimodal density ratio $dQ/dP$, the expected runtime of GRCS is upper bounded by $βD_{KL}[Q || P] + O(1)$ where $β\approx 4.82$, and its expected codelength is optimal. This makes GRCS the first REC algorithm with guaranteed optimal runtime for this class of distributions, up to the multiplicative constant $β$. This significantly improves upon the previous state-of-the-art method, A* coding (Flamich et al., 2022). Under the same assumptions, we experimentally observe and conjecture that the expected runtime and codelength of GRCD are upper bounded by $D_{KL}[Q || P] + O(1)$. Finally, we evaluate GRC in a variational autoencoder-based compression pipeline on MNIST, and show that a modified ELBO and an index-compression method can further improve compression efficiency.

Cited by 1Open access

Entropy, channel and line coding.

John H. Williamson (8917673), Melissa Quek (8917676), Iulia Popescu (8917679) et al. · Figshare · 2020

<p>The nested entropy coding, channel coding and line coding stages in a communication channel [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0233603#pone.0233603.ref060" target="_blank">60</a>].</p>

Cited by 0Open access

Multi-scale zerotree entropy coding

Iraj Sodagar, Hung-Ju Lee, P. Hatrack et al. · 2000

This paper describes the visual texture compression scheme adopted for MPEG-4 international standard. The scheme is based on the concept of multiscale zerotree wavelet entropy coding (MZTE) technique that provides different levels of scalability layer in terms of either spatial resolutions or picture quality. MZTE provides much improved compression efficiency and fine-gradual scalabilities. The MZTE scheme is adopted as the baseline technique for the visual texture coding profile in both MPEG4 video group and SNHC group.

Cited by 3

Source coding with Tsallis entropy

François Chapeau‐Blondeau, Agnès Delahaies, David Rousseau · Electronics Letters · 2011

An extension is presented to the source coding theorem traditionally based on the Shannon entropy and later generalised to the Rényi entropy. Another possible generalisation is demonstrated, with a lower bound realised by the Tsallis entropy, when the performance is measured by the generalised average coding length which is exhibited, and with the optimal codelengths expressed from the escort probability distribution, also known in nonextensive thermodynamics.

Cited by 13

Information entropy of coding metasurface

Tie Jun Cui, Shuo Liu, Lian-Lin Li · Light Science & Applications · 2016

Because of their exceptional capability to tailor the effective medium parameters, metamaterials have been widely used to control electromagnetic waves, which has led to the observation of many interesting phenomena, for example, negative refraction, invisibility cloaking, and anomalous reflections and transmissions. However, the studies of metamaterials or metasurfaces are mainly limited to their physical features; currently, there is a lack of viewpoints on metamaterials and metasurfaces from the information perspective. Here we propose to measure the information of a coding metasurface using Shannon entropy. We establish an analytical connection between the coding pattern of an arbitrary coding metasurface and its far-field pattern. We introduce geometrical entropy to describe the information of the coding pattern (or coding sequence) and physical entropy to describe the information of the far-field pattern of the metasurface. The coding metasurface is demonstrated to enhance the information in transmitting messages, and the amount of enhanced information can be manipulated by designing the coding pattern with different information entropies. The proposed concepts and entropy control method will be helpful in new information systems (for example, communication, radar and imaging) that are based on the coding metasurfaces.

Cited by 336Open access

Source Coding with Renyi's Entropy

Arun Choudhary, Satish Kumar, Arvind Kumar · 2013

A new measure ,  L called average code word length of order  is defined and its relationship with Renyi’s entropy of order  is discussed. Using ,  L some coding theorems are proved under the condition . 1 = 1 =   i N

Cited by 0

Entropy Measures for Controlled Coding

Giridharan Iyengar · 2007

In this paper, we present an approach to characterize video sequences using information theoretic measures. This characterization is then used to efficiently represent a volume of video. In a typical video sequence, sometimes texture reveals structure, in other cases motion does it. In addition, the temporal and spatial extents are variables. The attempt of this work is to build this structure by looking at a given region over a multiplicity of frames and scales using entropy measures. We then present a hierarchically structured class of coders that efficiently represent this volume of video. The structure built in the analysis stage is used to control and select amongst this class of coders. Keywords: Compression, Entropy, Mutual Information, Optical Flow, Quadrature Mirror Filters, Video Coding. 1 Introduction An underexplored benefit of digital television is that the signal can simultaneously carry the raw image reconstruction information as well as correlated descriptive data. In...

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