基于动态多阈值的多视点视频编码宏块模式快速选择算法

本文分析了多视点视频编码中宏块模式选择情况的统计特性,把宏块模式分为四类.提出了基于宏块模式类率失真均值的多阈值快速宏块模式选择算法及阈值的近似计算方法和动态更新算法,理论分析了该快速算法的编码率失真性能.实验结果表明,所提出快速算法在几乎不影响编码率失真性能的情况下,编码速度比多视点视频编码校验模型提高1.92倍到7.07倍.     

基于转移概率的多视点视频快速模式选择算法

针对多视点视频编码(MVC)中部分大宏块模式(SKI P/DIRECT模式,帧间16×16模式)相对于其它模式的计算复杂 度低,并且在编码所确定的最优模式中占有相当高比重的特点,本文提出一种基于转移概率 的多视点视频 快速模式选择算法。首先根据多视点视频当前编码宏块对应时间和视点间宏块及周围宏块的 位置几何关系, 建立宏块模式参考模型;其次比较参考模型中模式的时间相似度和视点间相似度;最后计算 模式之间的转 移概率,确定提前结束大宏块模式选择过程的阈值。实验结果表明,本文所提出的快速算法 平均节约MVC时间80.93%,编码质量平均下降0.04dB,码率平均增加0.27%。     

应用于多视点视频压缩的多参考B帧快速编码算法

基于H.264平台就多视点视频压缩中多参考帧技术存在计算复杂度高的现状,根据多视点视频序列特性,提出了一种针对多参考B帧的快速多视点视频编码压缩算法。新算法改进了多参考帧列表策略,并结合多视点视频序列的时空域相关性特性,提出了适用于多视点视频编码的参考帧列表调整策略。此外,还针对多种块模式编码引入了块模式预判策略。新算法在保证率失真性能的基础上,有效地降低了计算复杂度,提高了多视点视频编码速度。虽然本文是基于M-Picture编码结构实现了新算法,但它同样适用于其它应用多参考B帧预测技术的多视点视频编码结构中。     

3D-HEVC深度视频编码MERGE模式快速选择

针对3D-HEVC中多视点深度视频编码进行研究,提出了一种对深度视频参考视点的MERGE模式快速选择算法。考虑到多视点深度视频相邻视点间相关性和MVD格式中深度视频与彩色视频间相关性,在两个方向上的参考CU采用相同编码深度时,借鉴深度视频主视点PU模式信息以加快当前CU帧间模式选择速度。在深度主视点采用MERGE模式时,当前视点跳过其他的预测模式而直接采用MERGE模式。实验结果表明,在码率和图像质量基本不变的情况下,提出的算法可以有效地提高帧间模式选择速度。     

一种用于多视视频加深度联合编码的错误隐藏算法

ATM(AVC-based test model)测试模型实现了多视视频加深度(MVD)格式的联合编码,使得数据的压缩效率更高。然而,较高的压缩效率使得码流对传输错误非常敏感,极易产生错误扩散现象。针对ATM测试模型的编码顺序,提出一种用于MVD联合编码的错误隐藏算法。算法充分利用视点内、视点间及纹理视频与深度视频间的相关性,针对每个视点的不同特征提出了适应其视频特性的不同隐藏算法。实验表明,本文提出的算法可以在不增加算法复杂度的情况下,有效提高视频的主客观质量。     

基于块匹配的运动对象检测算法

针对交通监控视频图像的特点，本文对传统的块匹配算法做出改进，提出了一种新的块匹配算法。算法的改进主要在两个方面：引进了零运动阚值；采用自顶向下逐步细化的搜索算法。仿真结果表明，提出的算法对图像的噪声适应性强．而且跟踪对象准确。     

面向HBP编码格式的立体视频B帧整帧丢失分层错误隐藏算法

针对分层B帧(HBP)编码格式的立体视频B帧整帧丢失的问题,该文分析了双视点视频中存在的视点间运动矢量相关性,提出一种分层错误隐藏算法。该算法与当前主流的方法有两大不同:一是该算法采用分级隐藏,根据B帧的重要性等级不同采用不同的错误隐藏方法;二是该算法考虑了相邻视点序列之间的宏块运动矢量相关性。实验表明,该算法的性能优于当前常用的H.264多视点视频整帧丢失错误隐藏方法。     

利用最小Tsallis交叉熵的视频对象分割算法

提出了一种基于改进的最小Tsallis交叉熵的视频对象分割算法.在时域中采用帧间变化检测快速区分前景与背景,在空域中使用改进的最小Tsallis交叉熵设置自适应阈值,能更准确地对差分图像进行阈值分割,克服了传统的最小Tsallis交叉熵法阈值化容易失效的问题,然后利用形态学修正和差分交集技术获得精确的视频对象.实验结果...     

两种实时、低码率视频编码的运动估计搜索算法

先提出实时、低码率视频编码对运动估计搜索算法在运算时间和准确度上的要求，总结归纳了钻石搜索法和两步法的具体算法，通过与几种经典算法作比较，说明这两种算法更优，更适合用于实时，低码率视频编码，最后，以H．263的实现为例，说明了钻石搜索算法的具体实现。     

一种改进的运动估计快速搜索算法

运动估计是视频压缩中帧间预测编码的关键技术之一。在各个压缩标准中都广泛使用了基于块的运动估计技术。由于运动估计通常具有较大的运算量，因此对压缩性能具有重要的影响。文中分析了视频序列的特点和对现有的快速搜索算法深入理解的基础上提出了一种改进的快速运动估计搜索算法，实验表明该算法对压缩性能有较好的改进。     

Efficient multi-view video coding using inter-view information

Multi-view video coding (MVC) has been extended from H.264/AVC to improve the coding efficiency of multi-view video. This paper proposes a fast mode decision algorithm which can make an early decision on the correct mode partition to solve the issue of the enormous computational complexity. The best modes of the reference views are utilized to determine the complexity of the macroblock (MB) in the current view, the mode candidates needed to be calculated can then be obtained according to the complexity. If the complexity is low or medium, the search range can be reduced. The threshold of the rate-distortion cost for the current MB is calculated using the co-located and neighboring MBs in previously coded view and is utilized as the criterion for early termination. The motion vector difference in the reference view is applied to dynamically adjust the search range in the current MB. Experimental results prove that the proposed algorithm achieves a time saving of 81.05% for a fast TZ search and 87.85% for full search, and still maintains quality performance and bitrate.     

Coding statistics based fast mode decision for multi-view video coding

Reduction of high computational complexity of multi-view video coding (MVC) is necessary for realization in consumer electronics. Since mode decision is one of the key computational bottlenecks of multi-view video encoders, this paper proposes a coding statistics based fast mode decision algorithm. First of all, a rate–distortion cost based fast DIRECT mode decision algorithm early terminates the mode decision process if possible. Next, the candidates for Inter modes are reduced by taking the advantage of the correlation between an optimal mode and motion cost. The proper thresholds to reduce the candidates for the above two fast algorithms can be easily derived from exponential functions at run time. Finally, motion vector difference based motion characteristics is referred to further speed up the mode decision process of Inter modes. The experimental results show that the proposed scheme reduces up to 70.82% of encoding time with negligible degradation of RD performance.     

Color correction algorithm based on camera characteristics for multi-view video coding

Various types of multi-view camera systems have been proposed for capturing three dimensional scenes. Yet, color distributions among multi-view images remain inconsistent in most cases, degrading multi-view video coding performance. In this paper, we propose a color correction algorithm based on the camera characteristics to effectively solve such a problem. Initially, we model camera characteristics and estimate their coefficients by means of correspondences between views. To consider occlusion in multi-view images, correspondences are extracted via feature-based matching. During coefficient estimation with nonlinear regression, we remove outliers in the extracted correspondences. Consecutively, we generate lookup tables for each camera using the model and estimated coefficients. Such tables are employed for fast color converting in the final color correction process. The experimental results show that our algorithm enhances coding efficiency with gains of up to 0.9 and 0.8 dB for luminance and chrominance components, respectively. Further, the method also improves subjective viewing quality and reduces color distance between views.     

改进的Otsu算法及在运动目标检测中的应用研究

针对Otsu自适应阈值分割算法中阈值搜索精准度较低、效率不高的问题,本文结合视频图像序列的帧间相关性,利用遗传算法的全局寻优优势,及模拟退火算法较好的爬山性能,提出一种改进的Otsu算法,并与三帧差分法相结合应用于视频运动目标检测。实验证明,该算法相对Otsu算法和对比算法减少阈值分割中的寻优尝试次数,使最优阈值的选取更精确,并提高了目标检测效果。     

SIFT-flow-based color correction for multi-view video

During the multi-view video acquisition, color variation across the views tends to be incurred due to different camera positions, orientations, and local lighting conditions. Such color variation will inevitably deteriorate the performance of the follow-up multi-view video processing, such as multi-view video coding (MVC). To address this problem, an effective color correction algorithm, called the SIFT flow-based color correction (SFCC), is proposed in this paper. First, the SIFT-flow technique is used to establish point-to-point correspondences across all the views of the multi-view video. The average color is then computed based on those identified common corresponding points and used as the reference color. By minimizing the energy of the difference yielded between the color of those identified common corresponding points in each view with respect to the reference color, the color correction matrix for each view can be obtained and used to correct its color. Experimental results have shown that the proposed SFCC algorithm is able to effectively eliminate the color variation inherited in multi-view video. By further exploiting the developed SFCC algorithm as a pre-processing for the MVC, extensive simulation results have shown that the coding efficiency of the color-corrected multi-view video can be greatly improved (on average, 0.85 dB, 1.27 dB and 1.63 dB gain for Y, U, and V components, respectively), compared with that of the original multi-view video without color correction.     

一种基于H.264的快速运动估计算法

H.264是现有最重要数据压缩编码国际标准之一。同时快速运动估计算法一直是视频压缩中的研究热点。本文针对一些快速估计算法过早确定了搜索方向,容易陷入局部最小点,损失了搜索精度的情况,在原有基础上,运用菱形十字搜索算法(DCS)与阈值估计相结合的方法提高了运动估计的性能。实验结果表明,该算法可以用较小的搜索代价取得与全搜索(FS)相当的效果,并且在搜索速度方面优于钻石法(DS)。     

调整量最小的多视图像校正算法

在多视自由视点电视（FTV）系统中,摄像机阵列拍摄的多视视频存在垂直视差、且水平视差分布不均等问题,严重影响合成视频的质量效果。现有的多视图像校正方法虽然消除了垂直视差,但是校正图像过程中引入的旋转和平移失真较大,使人眼产生不舒适感。为此,本文提出一种适于平行摄像机阵列的多视图像校正算法,首先建立理想的摄像机安放位置,然后计算多视图像校正变换,将实拍图像映射到理想摄像机位置处,得到校正后图像。在设计理想的摄像机安放位置时,考虑人眼视觉特性,确保坐标轴旋转和平移调整量最小化,实现多视图像校正变换引入图像失真总量最小。实验表明,该算法不仅可以消除垂直视差,而且图像校正过程中引入的失真小,符合人眼视觉习惯,能有效改善合成视的图像质量,提高人眼观看舒适程度。      

自适应阈值的快速运动估计算法

分析了视频序列运动场的基本特征,利用运动和匹配误差两种相关性,提出自适应阈值的快速运动估计算法(AT-FME),随编码对象的内容和运动情况自适应地调整阈值和搜索模式.实验结果表明,在匹配质量和码率相同情况下,AT-FME可比UMHexagonS节省62%的运算量,是提高视频压缩编码效率的有效方法.