基于预测编码与DCT变换编码的比较

深入分析了预测编码与DCT变换编码的异同点，并从编码增益、块效应系数、预测与变换与变换前后的能量关系等多方面比较了两种编码的优缺点。     

A Unified Representation of Differential Pulse-Code Modulation (DPCM) and Transform Coding Systems

We consider a transform coding system that uses a lower-triangular transformation to uncorrelate the data. Based on this transformation we propose a generalized differential pulse code modulation (DPCM) system and show that at high bit rates it performs almost as well as coding by the method of principal components (Karhunen-Loeve transformation). This study connects the transform coding system to the DPCM encoder by showing that the proposed system simplifies to a standard DPCM encoder for Markov data.     

基于Galois域Reed-Solomon码的数据包层FEC编码软件实现

本文提出一种基于Galois域Reed-Solomon码的数据包层FEC编码软件实现方法。文中利用Galois域的运算封闭性和Reed-Solomon码的变换特笥解决了FEC编码等字长变换问题；通过查找表实现多项式运算，有效降低多项式运算的复杂度，提高了软件FEC编码的效率；文中还介绍了查找表的生成方法。实验表明，基于本文所提出的方法，能够用软件实现高效的数据包层FEC编/解码。     

3-puzzle量子计算的酉变换矩阵及逻辑线路

针对3-puzzle问题,运用量子计算方法,分析了节点扩展的酉变换矩阵.通过一个3-puzzle问题实例,对其进行了元素编码和节点状态编码,描述了具体的节点扩展酉变换矩阵,并运用量子受控非门逻辑线路实现了酉变换矩阵.讨论了N-puzzle量子计算的线路模型,对量子位的基态和最佳基态的制备作了分析.阐述了N-puzzle启发式搜索量子计算框架.     

几种常见编码方法的比较

通过对DFT／DCT、子带、小波变换、分形编码的特征分析，得出如下一些结论：DFT与DCT理论成熟，前者因存在复数计算，使得硬件结构较后者复杂，但DCT变换也因分块数限制，在还原图像时可能存在块效应；具有多分辨率分析的小波变换编码，虽然是目前变换编码中较为高级的一种，但也存在选择小波基函数的困难，子带编码具有并行处理和分层传输之优点，但镜像滤波器组的设计难以达到理论要求；根据事物间普遍存在的相似性建立起的分形编码，以其高压缩比换取图像的极端相似性，失真表现为整个屏幕的随机现象。     

Rotational transformation of signals

A coding procedure based on a rotational transformation is applied to reduce the effect of non-Gaussian impulsive noise in sampled data communication systems. The method, a near relative of the smearing techniques which have been suggested recently for continuous systems, provides a new and interesting view of many accepted coding systems and their relative properties. Attention is directed toward the effect of the transformation on the amplitude distribution of signals and to the existence of signals which do not benefit from a smearing technique in respect to their resistance to isolated impulse interference. The behavior of certain nonorthogonal transformations is also discussed in contrast to the purely rotational transformations.     

一种基于均匀环路的LDPC码校验矩阵的构造方法

LDPC码作为一种新的接近香农极限的信道编码方式,引起了广泛的注意。本文在总结出LDPC码校验矩阵的初等变换环路不变性和环路长度性质的基础上,提出了一种基于均匀环路的校验矩阵构造的新思路,而且还可以通过校验矩阵的矩阵初等变换得到其校验矩阵簇,在该簇中可以挑选编码复杂度低的LDPC码用在实际传输中。     

800/920/1200 bps改进型多带激励语音编码器的DSP实现

该文介绍了基于多带激励(MBE) 语音模型的改进型800/920/1200bps 语音编码器。该编码器采用二级离散余弦变换编码方案对逐帧变化的谱幅度参数进行自适应动态量化编码,大大减小了编码比特率,使得800~1200bps速率的MBE语音编码器的实现成为可能。该文重点介绍二级离散余弦变换编码方案及DSP硬件实现。     

Constrained Transform Coding and Surface Fitting

A constrained transform coding procedure is developed which is a combination of transform coding with differential pulse code modulation. The algorithm avoids block boundary mismatch errors, yet retains the coding efficiency of transform coding. A general theory of constrained transform coding is developed which includes the discrete cosine transformation and tensor products of splines as special cases. Results using the cosines and spines are given for two images. A complete discussion of the necessary linear algebra background is also given.     

一种快速DCT算法的研究

由于在H．261、H．263、MPEG-1以及MPEG-2等视频编解码标准中,运行频率最高的运算是离散余弦变换(DCT)。因此,运用DCT矩阵的基本性质和基本定律分析,提出了一种快速的离散DCT算法,对于视频编解码的实时处理有着重要的意义。     

服务质量控制粒度及基本细粒度编码算法研究

文章以视频服务质量控制的粒度为主线，分析了不同控制粒度的服务对网络状态变迁的响应特征．并探索了研究网络状态和QoS控制粒度之间的映射关系所必须解决的关键问题。在此基础上，进一步分析了位面编码、离散小波变换和MP变换编码三种基本细粒度视频编码算法的理论基础、实现方式和各自的特点。分析表明它们适用于不同的应用场合。     

基于DSP红外图像伪彩色处理的研究

根据红外图像的特点,在以室温热成像系统的基础上,对红外图像伪彩色编码进行了充分研究,提出了一种新的伪彩色编码。新编伪彩色编码算法,解决了RGB三色搭配的合理性和灰度范围集中时图像的难以辨别等问题。通过合理分配TMS320VC33硬件环境下存储资源,提高了算法的运行速度,使算法在DSP环境下工作稳定、运行良好。     

基于变步长约瑟夫遍历和DNA动态编码的图像加密算法

数字图像传输和存储的安全问题已成为信息安全研究的热点。该文提出一种基于变步长约瑟夫遍历和DNA动态编码的图像加密方法。首先将混沌映射产生的随机序列作为约瑟夫遍历的变步长，改进约瑟夫遍历问题，并采用改进的约瑟夫遍历对图像像素位置进行置乱；其次，动态选择DNA编码规则，对图像像素进行DNA编码，并与给定的DNA序列进行碱基运算；DNA编码规则的动态选择，很好地解决了DNA编码规则少所带来的安全隐患，提高了算法的安全性。最后通过密文反馈和混沌系统迭代来进一步增强算法的混淆和扩散特性。实验和安全性分析结果表明，该算法不仅对密钥的敏感性强，而且能有效抵御统计性分析和穷举分析等攻击操作。     

H.264中DCT/IDCT/Hadamard变换多时钟方式的FPGA实现

DCT/IDCT/Hadamard变换被广泛应用于多种视频编码标准中,而H.264/MPEG-4AVC作为新一代的视频压缩标准,它具有在相同图像质量下比其他视频压缩标准拥有更高的压缩率的特性[1],因此对于H.264/MPEG-4AVC中的DCT/IDCT/Hadamard变换的研究就有着十分重要的意义。对于H.264/MPEG-4AVC中变换算法进行分析,并且提出一种可用的高效的硬件实现电路结构,此电路结构能够并行计算4输入像素数据。     

Combined Kohonen neural networks and discrete cosine transform method for iterated transformation theory

Iterated transformation theory (ITT) coding, also known as fractal coding, in its original form, allows fast decoding but suffers from long encoding times. During the encoding step, a large number of block best-matching searches have to be performed which leads to a computationally expensive process. Because of that, most of the research efforts carried on this field are focused on speeding up the encoding algorithm. Many different methods and algorithms have been proposed, from simple classifying methods to multi-dimensional nearest key search. We present in this paper a new method that significantly reduces the computational load of ITT-based image coding. Both domain and range blocks of the image are transformed into the frequency domain (which has proven to be more appropriate for ITT coding). Domain blocks are then used to train a two-dimensional Kohonen neural network (KNN) forming a codebook similar to vector quantization coding. The property of KNN (and self-organizing feature maps in general) which maintains the input space (transformed domain blocks) topology allows to perform a neighboring search to find the piecewise transformation between domain and range blocks.     

Fractal image coding: a review

An approach to image coding based on a fractal theory of iterated contractive transformations defined piecewise is described. The main characteristics of this approach are that it relies on the assumption that image redundancy can be efficiently captured and exploited through piecewise self-transformability on a block-wise basis, and it approximates an original image by a fractal image, obtained from a finite number of iterations of an image transformation called a fractal code. This approach is referred to as fractal block coding. The general coding-decoding system is based on the construction, for an image to be encoded, of a fractal code-a contractive image transformation for which the original image is an approximate fixed point-which, when applied iteratively on any initial image of the decoder, produces a sequence of images which converges to a fractal approximation of the original. The design of a system for the encoding of monochrome digital images at rates below 1 b/pixel is described. Ideas and extensions from the work of other researchers are presented     

甚低码率视频压缩编码算法研究和标准化进展

本文综述了甚低码率视频编码算法和标准化进程的发展状况,概述了运动补偿,模型基,分形IFS及H.263和MPEG4等方面的进展,并讨论了未来可能的发展方向。     

MPEG-4中的Sprite编码技术及其发展

Sprite视频编码技术在MPEG-4中应用广泛,是其核心技术之一.Sprite编码技术将图像的镶嵌和图形的几何变换应用到压缩中,能有效地描述背景等一些特定的图像.介绍了Sprite概念、几种构建背景Sprite的方法以及Sprite编码技术在国内外的发展.     

Laplacian affine sparse coding with tilt and orientation consistency for image classification

Recently, sparse coding has become popular for image classification. However, images are often captured under different conditions such as varied poses, scales and different camera parameters. This means local features may not be discriminative enough to cope with these variations. To solve this problem, affine transformation along with sparse coding is proposed. Although proven effective, the affine sparse coding has no constraints on the tilt and orientations as well as the encoding parameter consistency of the transformed local features. To solve these problems, we propose a Laplacian affine sparse coding algorithm which combines the tilt and orientations of affine local features as well as the dependency among local features. We add tilt and orientation smooth constraints into the objective function of sparse coding. Besides, a Laplacian regularization term is also used to characterize the encoding parameter similarity. Experimental results on several public datasets demonstrate the effectiveness of the proposed method.     

一种基于MPEG-4的感兴趣区域视频编码新方法

本文提出了一种基于MPEG-4的感兴趣区域视频编码新方法.通过对感兴趣区边沿宏块采用强制帧内编码及宏块内预测编码时参考位置的自适应选择,该方法有效地抑制了数据噪声的扩散和传播.通过采用自适应宏块大小的运动估计/补偿算法,提高了感兴趣区特别是图像运动复杂的感兴趣区的编码效率及质量.在码率分配部分,本文方法通过计算不同区域的图像复杂性和能量,依据用户可设定的感兴趣权重因子不等重地分配可用码率资源.实验证明,本文方法较大程度改善了感兴趣区视频编码的压缩效率,提高了码率分配地灵活性和有效性.