一种嵌入式头肩图像编码方法

头肩序列图像是可视电话、会议电视等视频业务中常见的一种图像模式.本文将SPIHT算法与人脸检测算法相结合,提出一种嵌入式的头肩图像编码方法.首先采用人脸检测技术确定头肩图像中的人脸区域;然后产生人脸区的掩膜,并对LL子带中人脸区掩膜内的小波系数进行定标,以保证人脸区的小波系数能优先编码;最后采用SPIHT算法对人脸区和背景区进行编码.实验结果表明,与原来的SPIHT方法相比,这种方法可以保证人脸区域的重建质量好于背景区的重建图像.同时压缩后的码流仍然具有嵌入的特性,支持渐进传输.     

DNA序列数据压缩技术综述

DNA序列数据压缩技术是根据DNA数据特点针对性地构造编码算法,以提升整体压缩效率的数据处理方法.本文介绍了DNA序列的基本概念及数据特点,DNA序列压缩算法的一般性描述,DNA序列的典型压缩算法,以及评估DNA序列压缩算法性能的重要指标,并对DNA序列压缩算法未来的发展趋势做了展望.     

基于率失真优化和PSB系数位移的ROI编码新方法

小波系数移位和率失真优化的比率控制是实现ROI编码常用的两种策略.小波系数移位的方法能准确的恢复选择的ROI区域,但会影响编码的效率.而率失真优化的方法有好的编码效率但ROI区域重建精度受到影响.将两种机制结合,本文提出了一种率失真斜率提升和PSB系数移位相结合的ROI编码新方法.实验结果表明,新算法在同等编码效率及计算复杂度下,获得了良好的ROI重建精度.     

DNA Golay码的设计与分析

 DNA编码是DNA计算初始数据库中寡核苷酸序列的设计问题.合理的DNA编码可以提高实验的稳定性和正确性,从而确保DNA计算的成功率.本文给出DNA码字重量和DNA码字间Watson-Crick Hamming距离的定义;提出DNA Golay码的设计方法;分析了DNA Golay码的性质和规模;与随机搜索优码方法相比,DNA Golay码求解优码更加简单可行.     

一种新的3—D小波变换图像编码方法

基于图像序列三小波变换的视频编码技术是一种很有潜力的编码方法。本文针对目前实际中采用的三维小波变换只是一种准三维变换，不能提供对变换结果的统一描述等不足，推导了信号真正的三维小波变换的有关及其实现方法，在此基础上，我们将这种三维小波变换方法用于视频图像的编码，模拟结果表明这种编码结构具有良好性能，值得进一步的深入研究     

基于Memetic优化的智能DNA序列数据压缩算法

提出近似重复矢量(Approximate Repeat Vector,ARV)模型用于DNA序列冗余片段的描述.通过将数据生物信息学特征引入压缩预处理,并使用ARV矢量构造编码码本,提出了非对称DNA序列压缩算法BioLZMA-2.算法引入基于粒子群优化的Memetic改进方法CLIPSO-MA用于压缩码本的智能优化设计,有效提升了编码性能.在标准测试序列上的实验结果表明,BioLZMA-2可获得比现有DNA序列数据压缩方法更高的压缩率.     

一种高效的前向纠错码桶分配DNA存储解码方法

与传统存储方式相比,脱氧核糖核酸(DNA)存储的难点是测序序列中的插入和删除错误给信息解码过程带来了巨大挑战。针对具有1位纠错能力的前向纠错编码DNA存储,该文提出一种桶式分配策略提高解码的精度和效率。首先,搜索每个分组中所有测序读长的可识别DNA码,根据1位纠错能力确定其对应的合法编码;其次,根据每个可识别DNA码在测序读长的位置确定相应编码的最佳编码位置(即桶);最后,按照众数投票确定每个桶中的最终编码。仿真结果表明在0.10和0.05错误率条件下,平均解码准确率在20X测序深度时可达94%以上;在0.15错误率条件下,平均解码准确率在60X测序深度时可达90%以上。     

运动图象压缩编码中的三层小波分解

在序列图象编码中采用对帧间位移矢量进行估值的一类算法－－匹配算法，给出了一种利用三层小波分解序列图象运动补偿编码的方案。     

一种新的小波可视电话编码算法

针对极低比特率应用提出一种新的结合H.263与SLCCA的混合小波视频编码算法。在提出的算法中,首先,用基于H.263的微调运动估计减小时间冗余,用无遗漏覆盖块运动补偿保证运动补偿误差帧的连续性;第二,对运动补偿误差帧进行小波变换得到全局能量压缩;第三,用SLCCA组织和表示小波变换后的数据,最后,运动向量的水平和垂直分量分别用自适应算法编码,算法在A级测试序列Akiyo和B级测试序列Foreman（QFIF）上测试取得了良好效果。     

基于均匀网格编码量化的超光谱图像自适应压缩

提出一种基于小波系数分类的超光谱图像压缩方法．算法首先将各波段小波分解并将所得子带划分成子块，而后根据子块活动性将其分类．在分类基础上，使用预测差分技术去除谱间冗余，此过程中分别求取各子类的预测系数以反映子带的局部相关性，而后利用均匀网格编码量化方法来量化残差系数序列，最后使用自适应算术编码对量化码字进行熵编码，为使编码器能在所有系数序列中最优地分配比特，本文提出一个基于序列统计特性和网格编码量化器率-失真特性的比特分配算法，实验证明该方法能高效地压缩超光谱图像，表现出优异的压缩性能。     

Adaptive lossless compression of skeleton sequences

The increasing importance of skeleton information in surveillance big data feature analysis demands significant storage space. The development of an effective and efficient solution for storage is still a challenging task. In this paper, we propose a new framework for the lossless compression of skeleton sequences by exploiting both spatial and temporal prediction and coding redundancies. Firstly, we propose a set of skeleton prediction modes, namely, spatial differential-based, motion vector-based, relative motion vector-based, and trajectory-based skeleton prediction mode. These modes can effectively handle both spatial and temporal redundancies present in the skeleton sequences. Secondly, we further enhance performance by introducing a novel approach to handle coding redundancy. Our proposed scheme is able to significantly reduce the size of skeleton data while maintaining exactly the same skeleton quality due to lossless compression approach. Experiments are conducted on standard surveillance and Posetrack action datasets containing challenging test skeleton sequences. Our method obviously outperforms the traditional direct coding methods by providing an average of 73% and 66% bit-savings on the two datasets.     

Morphological shape representation for very low bit-rate video coding

Region-based coding schemes are among the most promising compression techniques for very low bit-rate applications. They consist of image segmentation, contour and texture coding. This paper deals with the use of the geodesic skeleton as a morphological tool for contour coding of segmented image sequences. In the geodesic case, already coded and known regions are taken into account for the coding of contours of unknown regions. A new technique is presented for the entropy coding of the coordinates of the skeleton points exploiting their special spatial distribution. Furthermore, a fast algorithm for the reconstruction of the skeleton points is given based on hierarchical queues. In the case of numerous isolated contour arcs (for example error coding in a motion prediction loop), the geodesic skeleton proofs higher efficiency than traditional methods. Results at very low bit-rates are presented and compared to standard methods confirming the validity of the chosen approach.     

Block motion compensated coding of interlaced sequences using adaptively deinterlaced fields

Video coding algorithms using block motion compensation were first developed for progressively scanned sequences and as such, are not entirely suitable for interlaced sequences In this paper we present a new approach for block-based coding of interlaced sequences. This proposed algorithm processes the interlaced sequence as a sequence of even and odd fields by using the last decoded field, adaptively deinterlaced, for the motion compensated prediction of the current field. The deinterlacing is performed at the decoder and no extra information has to be sent to guide the adaptation. The algorithm is a simple and efficient alternative to algorithms using the last two decoded fields for the motion compensated prediction of the current field. The new approach can easily incorporate the use of fast search algorithms and allows the use of true half-pixel accuracy in the estimates of the vertical component of the motion vectors. In HDTV sequences tested, this algorithm achieves superior performance due to this half-pixel accuracy.     

H.264/AVC帧内4×4预测算法的高效流水线结构

H.264编码器中的帧内4×4预测部分具有严重的数据依赖性,它的硬件化设计很难采用流水线实现,从而导致关键路径很长,硬件利用率很低,成为H.264编码器设计中的一个瓶颈。针对这个问题,在不减少预测模式和不增加系统资源的前提下,提出了一种新的结构,它通过利用原始像素进行模式判决和利用重构像素进行帧内预测的方法,可以使帧内预测与重构循环完全流水线实现,基本上达到了100%的硬件利用率,而且没有明显的PSNR损失。所提出的硬件结构可在215个时钟周期内完成一个宏块的帧内4×4预测。用SMIC 0.13μm工艺库综合,结果显示该结构最高可运行在250 MHz,面积约为116千门,可支持4 096×2 160@30 f/s(帧/秒)视频序列的实时编码。     

一种H.264/AVC帧内4x4预测算法的高效流水线结构

H.264编码器中的帧内4x4预测部分具有严重的数据依赖性,它的硬件化设计很难采用流水线实现,从而导致关键路径很长,硬件利用率很低,成为H.264编码器设计中的一个瓶颈。针对这个问题, 在不减少预测模式和不增加系统资源的的前提下,本文提出了一种新的结构,它通过利用原始像素进行模式判决和利用重构像素进行帧内预测的方法,可以使帧内预测与重构循环完全流水线实现,基本上达到了100%的硬件利用率,而且没有明显的PSNR的损失。本文所提出的硬件结构可在215个时钟周期内完成一个宏块的帧内4x4预测。用SMIC 0.13um工艺库综合,结果显示该结构最高可运行在250M,面积约为116K门,可支持4096x2160@30fps视频序列的实时编码。     

A Segmentation-Based Chroma Intra Prediction Coding Scheme for H.264/AVC

In this paper, we propose a novel segmentation-based intra prediction coding scheme for low-bitrate video coding. Different coding schemes are separately designed for the luma and chroma components in our proposed method. The traditional block-based coding scheme is still used for the luma components, and the segmentation-based coding scheme is developed for the chroma components. The segmentation operation is used for the reconstructed luma components, which groups similar pixels together and produces a set of homogenous regions. Here, these local and homogenous regions are referred to superpixels. By utilizing the spatial correlation between the luma and chroma planes, we transfer the segmentation result of the luma components to the chroma components, which will not induce any side information in the chroma intra prediction coding. Instead of using the macroblock (MB) as the coding unit, the proposed method implements the chroma intra prediction in each superpixel, and the original pixels in each superpixel are employed to substitute the neighboring reconstructed samples in the prediction process. The experimental results show that the proposed method can achieve an average 0.20 dB and up to 0.63 dB coding gains in comparison to the directional intra prediction scheme for H.264/AVC low-bitrate video coding.     

基于AVS2的色度扩展视频编码的设计和实现

色度扩展视频编码是当前视频编码领域的一个热点研究课题。该文提出基于AVS2平台的色度扩展视频帧内编码的实现方案。仿444/422编码方案通过将输入图像中的色度分量下采样后,使用原有的420方式进行编码,以实现444/422编码。进一步,该文将帧内预测及环路滤波等编码模块无缝扩展到相应的444/422格式,实现444/422帧内预测编码。实验结果表明,对444格式和422格式序列,在高码率的情况下444/422帧内预测编码与仿444/422编码相比,U/V平均BD-rate的减少分别为31.44%/31.72%和18.85%/19.3%,而Y分量平均BD-rate的增加仅为0.5%。其中422色度帧内预测过程的算法优化减少Y/U/V BD-rate最高可达5.66%。与HEVC RExt编码相比,在低码率时,444/422帧内预测编码取得了更好或相近的编码性能。     

Segmentation-based compression scheme for 3D animated models

This paper presents an efficient compression algorithm for animated three-dimensional (3D) meshes. First, a segmentation approach is applied to achieve the motion estimation. The main idea is to exploit the temporal coherence of the geometry component by using the heat diffusion properties. The motion of the resulting regions is accurately described by 3D affine transforms. These transforms are computed at the first frame to match the subsequent ones. Second, in order to achieve a good compression performance, an efficient rate control mechanism is proposed to quantize the temporal prediction errors. At this stage, a rate-distortion model is used for quantizing the residual information. Comparative coding tests, for irregular 3D mesh sequences, were conducted to evaluate the coding efficiency of the proposed compression scheme. Simulation results show very promising performances.     

Wavelet-based lossy-to-lossless ECG compression in a unified vector quantization framework

In a prior work, a wavelet-based vector quantization (VQ) approach was proposed to perform lossy compression of electrocardiogram (ECG) signals. In this paper, we investigate and fix its coding inefficiency problem in lossless compression and extend it to allow both lossy and lossless compression in a unified coding framework. The well-known 9/7 filters and 5/3 integer filters are used to implement the wavelet transform (WT) for lossy and lossless compression, respectively. The codebook updating mechanism, originally designed for lossy compression, is modified to allow lossless compression as well. In addition, a new and cost-effective coding strategy is proposed to enhance the coding efficiency of set partitioning in hierarchical tree (SPIHT) at the less significant bit representation of a WT coefficient. ECG records from the MIT/BIH Arrhythmia and European ST-T Databases are selected as test data. In terms of the coding efficiency for lossless compression, experimental results show that the proposed codec improves the direct SPIHT approach and the prior work by about 33% and 26%, respectively.