回归分析建模的自适应SKIP模式预选算法

SKIP模式在最佳编码模式中占相当大的比例.SKIP模式预选可以有效减少模式选择的计算复杂度.在现有的SKIP模式预选算法中,该阈值往往不能和视频内容自适应.用回归分析建模的思路,提出了一种内容自适应的SKIP模式预选算法(CASMED),通过一个能够反映当前编码宏块特性的变量来自适应地对阈值模型进行调整.结果证明,该算法在编码性能损耗几乎为零的情况下,大大降低了模式选择算法的复杂度.     

基于低复杂度自适应帧的WVSN视频编码方法

针对WVSN视频节点资源受限与视频编码方法复杂度高等问题,提出一种基于低复杂度自适应帧的视频编码方法。由"隔块-对角线"差异值计算方法求得差异值,建立自适应帧传输机制,避免逐帧判断,减少计算量。帧内图像采用多边形DCT裁剪JPEG压缩,减少二维DCT计算复杂度。实验结果表明,该方法在保证视频质量前提下,能有效降低视频编码复杂度,与无裁剪JPEG图像压缩相比,当前帧、差分帧JPEG压缩DCT计算量分别减少9.4%、56.3%;与M-JPEG视频编码相比,平均PSNR减少3.1%情况下,平均文件大小显著减少55.0%。     

一种基于差错估计的H.264视频容错算法

针对最新的视频编码标准H．264,设计了一种基于差错估计的容错算法。该算法结合信道条件,估计差错在视频编码帧之间的扩散;根据每个宏块差错的程度,自适应地判断是否对该宏块进行帧内编码,从而抑制差错的积累。在存在反向信道的环境中,该算法可以利用解码器反馈的实际宏块错误信息,跟踪差错扩散,对其进行更准确的估计,以提高容错性能。仿真表明,在各种信道条件下,该算法相对于随机帧内宏块更新算法．重建图像平均峰值信噪比有1．3～2．5dB的提高。同时,该算法对信道估计的要求不高,运算量和存储量的增加较低,具有实用性。     

一种多视点视频编码的宏块模式快速选择新算法

分析了多视点视频编码中宏块模式的选择情况,提出了顺序可选宏块模式集的概念.比较分析了率失真代价最优宏块模式和最省时间可选宏块模式的搜索过程,讨论了编码宏块模式为最省时间可选宏块模式对率失真性能的影响,并在此基础上提出了基于顺序可选宏块模式集的快速宏块模式选择算法.实验结果表明,所提出算法在基本保持率失真性能的情况下,能明显降低宏块模式选择的复杂度,编码速度比多视点视频编码校验模型提高3.2倍到5.8倍.     

基于自适应分段跳过规则的视点合成优化方法

对目前三维高效视频编码(3D-HEVC)标准的性能进行了分析,针对其深度图编码采用的合成视点失真变化(SVDC)计算复杂度高的问题,提出了一种基于自适应分段跳过规则的视点合成优化(VSO)方法。考虑到原始方法跳过了深度数据没有变化的模块或像素行,但忽略了可以在VSO中跳过的较小区域,该方法首先根据深度零失真准则和纹理平滑度准则判别出深度图中不会造成合成视点失真的区域,然后在深度图编码进行SVDC计算前基于自适应分段规则来提前跳过上述零失真区域,最后终止该区域的SVDC计算过程,有效地降低编码复杂度。对比实验结果证明了该方法的有效性,能在保持编码质量不变的前提下,平均减少14.2%的编码时间。     

H.264帧内预测与帧间块模式选择快速算法

针对H.264帧间预测时的多子块模式选择和帧内预测的多模式选择问题,提出了一种实用的基于统计门限的模式快速选择算法,通过门限设定有效限定了编码模式的选择范围.多组视频序列的实验结果表明,基于统计门限的帧内预测模式选择算法在Ⅰ帧的PSNR值有微小变化的情况下,大大降低了编码时间,Ⅰ帧的编码时间降低17%～23%,PSNR下降不到0.4%.基于统计门限的帧间块模式选择算法使得平均PSNR值下降了0.047dB(PSNR最大下降不到1%),但是相对全模式预测时,编码器速度提高了20%～30%.     

一种快速内插滤波方法

自适应内插滤波器的提出,增加了编码器的复杂度。为了降低运算复杂度,分析自适应内插滤波器的编码过程并提出一种快速内插滤波的方法。该算法计算出前后两帧之间相对变化程度,当变化程度在预定范围内,则使用前一帧中内插滤波器,从而避免复杂的计算。实验结果表明:对于运动比较简单的视频序列,在性能降低可以忽略的条件下,可以降低运算复杂度,节省编码时间。     

改进的空域平滑的边信息插值算法

针对分布式视频编码(DVC)中的边信息重建问题,提出了一种空域平滑的边信息重建算法.该算法在关键帧之间的前向运动估计时,设置代价函数阈值保证目标运动轨迹的线性连续.对于运动平稳区域,采用双向运动补偿插值生成边信息;对于其它区域,在关键帧中确定多个候选块,并选择与待插值块的4个相邻块具有最小边界匹配误差的候选块作为边信息...     

一种快速的基于稀疏表示的人脸识别算法

基于稀疏表示的人脸识别算法（SRC）识别率相当高,但是当使用l1范数求最优的稀疏表示时,大大增加了算法的计算复杂度,矩阵随着维度的增加,计算时间呈几何级别上升,该文提出利用拉格朗日算法求解矩阵的逆的推导思路,用一种简化的伪逆求解方法来代替l1范数的计算,可将运算量较高的矩阵求逆运算转变为轻量级向量矩阵运算,基于AR人脸库的实验证明,维度高的时候识别率高达97%,同时,计算复杂度和开销比SRC算法大幅度降低95%。     

基于嵌入式小波编码的DEM快速无损压缩算法

为减少网络地理信息系统(GIS)海量数字高程模型(DEM)数据的存储与传输数据量,提出了一种基于嵌入式小波编码的DEM快速无损压缩算法--FEC算法,此算法编解码快速,压缩位流具有分辨率嵌入、感兴趣区域嵌入和质量嵌入特点.对2/6可逆整数小波变换系数的每级分辨率数据按照区域划分分区,利用时空邻居关系挖掘每个分区子带的数据冗余,对其系数的每一个位面在一次扫描中完成三个子编码过程的系数建模重组与自适应二进制游程Golomb_Rice熵编码.实验数据表明,FFC算法与JPEG2000算法相比,编码、解码时间分别减少了36.04%和44.49%,而压缩比仅仅降低了8.05%;与SPIHT算法相比,编码、解码时间分别减少了32.28%和37.49%,而压缩比仅仅降低了4.58%;与GZIP算法相比,压缩比提高了79.63%;与n点最优预测算法相比,压缩比提高了9.23%.FEC算法在保持良好的压缩性能的同时,大幅度减少了编解码时间.     

一种利用离散余弦变换频谱图和小波变换图像编码的语音编码算法

语音、图像编码技术是现代数字通信的核心技术,通常是分开进行的,提出了一种利用二维DCT频谱图和小波变换图像编码的语音编码算法.深入分析了算法实现的关键技术——语音信号的二维DCT频谱图,仿真实现了该编码算法,对一段语音的处理结果表明,小波分解系数置零率为83.1941％,压缩后保存能量92.0867％,合成语音达到“优...     

Efficient bit‐plane coding scheme for fine granular scalable video coding

In this paper, we propose a new efficient bit‐plane coding method for fine granular scalable (FGS) video coding. The general structure of the proposed bit‐plane coding method is based on the traditional bit‐plane coding scheme in MPEG‐4 FGS. However, to enhance coding efficiency of bit‐plane encoding, we apply an efficient probability estimation scheme through employing the binary arithmetic coding. For probability estimation, various context models are designed to take advantage of the characteristics of each bit‐plane as well as the correlations of symbols among different bit‐planes. Experimental results show that the proposed FGS coding scheme provides better coding performance, compared to the well‐known FGS coding schemes in MPEG‐4 FGS and JSVM. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 16, 113–120, 2006.     

Colour image coding scheme using absolute moment block truncation coding and block prediction technique

Abstract

A predictive colour image compression scheme based on absolute moment block truncation coding is proposed. In this scheme, the high correlations among neighbouring image blocks are exploited by using the similar block prediction technique. In addition, the bit plane omission technique and the coding of quantisation levels are used to cut down the storage cost of smooth blocks and complex blocks respectively. According to the experimental results, the proposed scheme provides better performance than the comparative schemes based on block truncation coding. It provides better image qualities of compressed images at low bit rates. Meanwhile, it consumes very little computational cost. In other words, the proposed scheme is quite suitable for real time multimedia applications.     

Bandwidth efficient concatenated coding schemes

Concatenated coded modulation is a powerful method for constructing coding schemes with large coding gain and low decoding complexity. For the concatenated scheme, the outer code has redundancy and the overall transmission rate is reduced. The problem of bandwidth expansion can be overcome by two procedures. First, the code rate of inner codes is increased with a special coding design. Second, a two-level concatenated scheme is constructed to compensate the rate loss. This way, the low-complexity concatenated coded modulation schemes can be designed without bandwidth expansion as compared with the uncoded scheme.     

Superresolution with nonorthogonal polarization coding

One can achieve high-resolution (superresolution) imaging, beyond the classical limit, by exploiting certain degrees of freedom such as time and polarization for the object under consideration. We present an implementation, based on polarization coding, that requires insertion of a single mask into the object plane followed by postprocessing of the detected signal. We describe the procedure and provide experimental evidence for the implementation of the proposed technique.     

Visual communication with retinex coding

Visual communication with retinex coding seeks to suppress the spatial variation of the irradiance (e.g., shadows) across natural scenes and preserve only the spatial detail and the reflectance (or the lightness) of the surface itself. The separation of reflectance from irradiance begins with nonlinear retinex coding that sharply and clearly enhances edges and preserves their contrast, and it ends with a Wiener filter that restores images from this edge and contrast information. An approximate small-signal model of image gathering with retinex coding is found to consist of the familiar difference-of-Gaussian bandpass filter and a locally adaptive automatic-gain control. A linear representation of this model is used to develop expressions within the small-signal constraint for the information rate and the theoretical minimum data rate of the retinex-coded signal and for the maximum-realizable fidelity of the images restored from this signal. Extensive computations and simulations demonstrate that predictions based on these figures of merit correlate closely with perceptual and measured performance. Hence these predictions can serve as a general guide for the design of visual communication channels that produce images with a visual quality that consistently approaches the best possible sharpness, clarity, and reflectance constancy, even for nonuniform irradiances. The suppression of shadows in the restored image is found to be constrained inherently more by the sharpness of their penumbra than by their depth.     

质量，效率与成本——技术革新提升喷码质量

对于任何一条为商品带来成功经济效益的包装生产线，质量、效率与成本——三大要素无疑缺一不可。至于这三者之间的关系，有人说是“减少成本与提高效率，质量是永恒的主题”；有人则认为“好质量＋高效率=低成本”……如何表述并不重要；重要的是，只有清晰三者的关系，才能够让企业永恒追求的利润和效益增长点不至于成为他们触手不及的挑战。[编者按]     

Grefenstette编码法的MATLAB实现

本文在MATLAB环境下编程实现针对TSP问题的Grefenstette编码法 ,并将其同基本遗传算法相结合 ,仿真求解一个15点的TSP问题。仿真实验的结果验证了程序的有效性。