基于对象的小波变换在MPEG-4任意形状图像编码中的应用

任意形状图象对象的变换编码方法是MPEG-4视频编码实现的核心技术之一.该文对基于对象的小波变换在任意形状图象编码算法中的应用给予了详尽的论述.基于对象的小波变换包含两个步骤一是针对任意形状对象进行外插,使其可以运用规范的小波变换;二是进行小波系数的编码选择,以消除外插所产生的冗余.实验结果表明基于对象的小波变换与诸如SADCT等方法具有相似的低复杂度,性能相当;并且,在低比特率的情况下,其编码效果要优于SADCT.     

基于对象的小波变换的MPEG—4任意形状图像编码中的应用

任意形状图象对象的变换编码方法是MPEG－4视频编码实现的核心技术之一。该文对基于对象的小波变换在任意形状图象编码算法中的应用给予了详尽的论述,基于对象的小波变换包含两个步骤：一是针对任意形状对象进行外插,使其可以运用规范的小波变换;二是进行小波系数的编码选择,以消除外插所产生的冗余,实验结果表明：基于对象的小波变换与诸如SADCT等方法具有相似的低复杂度,性能相当,在低比特率的情况下,其编码效果要优于SADCT。     

基于整型零树小波变换的编码研究与应用

结合嵌入式零树小波(EZW)系数的统计特性,提出了整型零树小波变换算法,该算法通过计算小波变换的整数可逆矩阵分解,得到可以整数实现的可逆矩阵变换;再利用得到的分解矩阵依次对图像样本进行变换;最终将变换得到的系数用EZW进行编码,实验结果表明,整型零树小波在低比特率下明显优于其他压缩编码,使变换后的图像数据能够保持原图像在各种分辨率下的精细结构,在编解码过程中,可根据需要随时停止编解码过程,得到不同精度和不同码率的恢复图像,适合并行实时处理。     

基于人眼视觉特性的任意形状ROI编码

研究了等级树集分割编码方法(SPIHT)在任意形状感兴趣区域(ROI)编码中的应用．根据SPIHT算法的特性、ROI小波系数提升后的特点及人眼视觉特性,提出基于人眼视觉特性的任意形状ROI编码方法．该方法综合了一般基于尺度的方法和最大平移法的优点：可调节ROI与背景(BG)的相对重要程度;支持任意形状ROI编码．另外,与最大平移法相比,本文方法具有更好的主观视觉效果,理论分析和仿真实验都表明本文方法优于MPEG-4中规定的视频静态纹理视觉对象(VO)编码．     

基于EZW图像压缩算法改进的可行性研究

在嵌入式零树小波编码(EZW)算法的基础上,为实现快速高质量数字图像压缩性能,探讨消除树间系数节点冗余以进一步实现压缩的可能性,并给出避免多次重复后代子孙系数节点扫描的改进策略.首先,根据EZW算法中全局阈值提取的重要系数在各子带的分布特性,给出一个各子带重要系数的自适应阈值序列.然后,依据归一化能量序列熵值进一步压缩各子带的重要系数,以实现消除小波树的树间冗余.最后,采用小波树逆编码完成对图像数据的编码输出.     

基于边缘矩阵的链编码追踪算法

提出了一种基于边缘矩阵的链编码追踪算法,并引入“边缘矩阵”的数据结构,记录像素边缘的一些信息,以此辅助链编码追踪算法的运行。该算法不仅能追踪任意形状复杂区域的链编码,而且它的计算复杂性是线性的。该算法还可为给出表示链编码之间包含关系的树结构和其它分析打下了基础。     

基于小波变换的图像零树压缩感知方法

稀疏性是压缩感知的前提,然而,自然图像通常不是稀疏的,因此对图像直接应用压缩感知算法很难取得高压缩效率.针对图像信号,将编码思想融入压缩感知理论,提出一种简单有效的零树压缩感知方法.该方法先利用零树思想辅助压缩感知测量,在得到测量值的同时编码重要系数的位置;然后提出零树追踪重构算法,通过精确解码重要系数位置来重构原始图像小波系数,提高重构精度.实验结果表明,相比于现有匹配追踪算法和EZW算法,本文方法有更高的压缩比和更好的图像重构质量.     

计算机图形编码转换时形状分析的改进

为了解决四又树编码在转换时,同一形状和大小的多边形图形可能会产生不同的四叉树,不利于形状分析和模式识剐.借鉴四叉树编码的分割方法和霍夫曼编码的原理,对四叉树的每个叶子结点进行编码,因为霍夫曼编码是用二又树结构表示,一组编码只对应一种编码树,最后利用Morton码对节点进行压缩编码.     

三对角方程组通用性迭代解法

在文献(四川师范大学学报:自然科学版,2008,31(2):187-188.)的基础上,提出一种对任意相容性三对角方程组均有效的迭代算法,证明该算法的收敛性,并设计并行处理方案和测试用例.该算法基本思想是:利用三对角方程组系数矩阵中行向量的部分正交性,将三对角方程组系数矩阵分为3组,使组内行向量相互正交,通过压缩存储将3组行向量压缩为3个行向量,从第一组开始用文献的方法在3组之间循环迭代,并取加速因子为1.该算法的特点是:对任意相容性三对角方程组均收敛,易于并行且节省存储空间,特别适合大型和超大型方程组的求解.     

应用时变小波包零树编码实现心电数据的高效压缩

为减少传统小波零树编码算法中孤立零的出现,以确保编码压缩后信号的熵减,提出了时变小波包零树编码算法,构建了最优小波包基下低冗余映射关系,同时考虑到心电信号自身的时域相关性,将时频域结合考虑,进一步降低了信息熵,最终明显改善了压缩效果.实验结果表明,该方法保留了小波零树编码可以实现累进传输编码的优点,并且取得了更好的压缩性能.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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