Enabling stereoscopic high dynamic range video

Stereoscopic and high dynamic range (HDR) imaging are two methods that enhance video content by respectively improving depth perception and light representation. A large body of research has looked into each of these technologies independently, but very little work has attempted to combine them due to limitations in capture and display; HDR video capture (for a wide range of exposure values over 20 f-stops) is not yet commercially available and few prototype HDR video cameras exist. In this work we propose techniques which facilitate stereoscopic high dynamic range (SHDR) video capture by using an HDR and LDR camera pair. Three methods are proposed: one based on generating the missing HDR frame by warping the existing one using a disparity map; increasing the range of LDR video using a novel expansion operator; and a hybrid of the two where expansion is used for pixels within the LDR range and warping for the rest. Generated videos were compared to the ground truth SHDR video captured using two HDR video cameras. Results show little overall error and demonstrate that the hybrid method produces the least error of the presented methods.     

面向多用户的高动态范围视频动态范围可分级编码

提出了面向多用户的高动态范围(HDR,high dynamic range) 视频动态范围可分级编码方法,并利用视觉掩蔽特性抑制了噪声,提高了动态范围可 分级编码的效率。首先,考虑HDR视频感知特性,提出了动态范围可分级模型(DRSM,dynamic range scalable model),将不同动态范围级的HDR视频分解成为一个标准动态范围(SDR,s tandard dynamic range) 视频和多个残差信号帧(RSFs,residual signal frames)序列。然后,结合亮度掩蔽效应和 人眼感知特性,对 RSFs进行量化和滤波处理,滤除残差中的零散数据点,保留RSFs相邻动态范围级之间的整体 差异信息, 提高RSFs的编码效率。最后,在解码端重建得到SDR视频和各个动态范围级的HDR视频,以适 应多用 户端MDR显示设备。结果表明,所提出方法能在保持重建HDR视频的主观感知质量的同时降低 编码码率, 并在全帧内预测编码模式下,相同HDR-VDP-2.2和PSNR分值时,BD-rate (Bjntegaard D elta rate)平均节省了32.03%和31.28%,其编 码率失真性能有明显提升。     

HDR-VQM: An objective quality measure for high dynamic range video

High dynamic range (HDR) signals fundamentally differ from the traditional low dynamic range (LDR) ones in that pixels are related (proportional) to the physical luminance in the scene (i.e. scene-referred). For that reason, the existing LDR video quality measurement methods may not be directly used for assessing quality in HDR videos. To address that, we present an objective HDR video quality measure (HDR-VQM) based on signal pre-processing, transformation, and subsequent frequency based decomposition. Video quality is then computed based on a spatio-temporal analysis that relates to human eye fixation behavior during video viewing. Consequently, the proposed method does not involve expensive computations related to explicit motion analysis in the HDR video signal, and is therefore computationally tractable. We also verified its prediction performance on a comprehensive, in-house subjective HDR video database with 90 sequences, and it was found to be better than some of the existing methods in terms of correlation with subjective scores (for both across sequence and per sequence cases). A software implementation of the proposed scheme is also made publicly available for free download and use.     

基于3D-SPIHT的立体视频图像压缩编码

该文提出一种新的立体视频编码方案:在辅助序列中进行视差补偿预测和三维等级数集合分区(3D-SPIHT)编码,3D-SPIHT算法建立在真三维小波分解基础上,通过定义一种新的时空方向树结构,实现了静止图像SPIHT算法的三维扩展,实验结果表明该方案的编码性能略高于传统方案,具有较低的计算复杂度,所产生的嵌入式辅助序列码流,可根据通道带宽自适应调整输出码率,最大限度地提高辅助序列的质量。     

Methods for improving the tone mapping for backward compatible high dynamic range image and video coding

Backward compatibility for high dynamic range image and video compression forms one of the essential requirements in the transition phase from low dynamic range (LDR) displays to high dynamic range (HDR) displays. In a recent work [1], the problems of tone mapping and HDR video coding are originally fused together in the same mathematical framework, and an optimized solution for tone mapping is achieved in terms of the mean square error (MSE) of the logarithm of luminance values. In this paper, we improve this pioneer study in three aspects by considering its three shortcomings. First, the proposed method [1] works over the logarithms of luminance values which are not uniform with respect to Human Visual System (HVS) sensitivity. We propose to use the perceptually uniform luminance values as an alternative for the optimization of tone mapping curve. Second, the proposed method [1] does not take the quality of the resulting tone mapped images into account during the formulation in contrary to the main goal of tone mapping research. We include the LDR image quality as a constraint to the optimization problem and develop a generic methodology to compromise the trade-off between HDR and LDR image qualities for coding. Third, the proposed method [1] simply applies a low-pass filter to the generated tone curves for video frames to avoid flickering during the adaptation of the method to the video. We instead include an HVS based flickering constraint to the optimization and derive a methodology to compromise the trade-off between the rate-distortion performance and flickering distortion. The superiority of the proposed methodologies is verified with experiments on HDR images and video sequences.     

摄录像技术设备的发展现状与趋势

以时间为线索，阐述世界内电电视系统中主要技术环节的摄录像技术设备的变革过程，分析摄录像技术设备的应用现状、主要技术特点和未来发展趋势。     

Object-based stereo video compression using fractals and shape-adaptive DCT

Based on the classical fractal video compression method, an improved object-based stereo video compression scheme with Shape-Adaptive DCT is proposed in this paper. Firstly, we use more effective macroblock partition scheme instead of classical quadtree partition scheme; thus reducing the block searching strategy. The stereo fractal video coding is proposed which matches the macroblock with two reference frames in left and right view results in increasing compression ratio and reducing bit rate when transmitting compressed stereo data. The stereo codec combines the Motion Compensation Prediction (MCP) and Disparity Compensation Prediction (DCP). Fractal coding is adopted and each object is encoded independently by a prior video segmentation alpha plane, which is defined exactly as in MPEG-4. The testing results with the nature monocular and stereo video sequences provide promising performances at low bit rate coding. We believe it will be a powerful and efficient technique for the object-based monocular and stereo video sequences coding.     

Binocular perception based reduced-reference stereo video quality assessment method

A new reduced-reference (RR) stereo video quality assessment method is proposed in this paper by considering temporal characteristics of video and binocular perception in human visual system (HVS). Firstly, motion intensity is utilized to extract RR frames for the purpose of temporal characteristics in stereo video. Secondly, according to internal generative mechanism of HVS, fusion and rivalry in the process of binocular perception is modeled, and the RR frames are divided into binocular fusion portion and binocular rivalry portion. Then, RR frame quality indicators are computed for these two portions. Finally, the RR frame quality indicators of the original and distorted frames are compared. A temporal pooling strategy is utilized on these quality indicators to obtain final stereo video quality score, where the motion intensity is used for toning the pooling parameters. Experimental results show that the proposed method has better performances when compared to other state-of-the-art quality assessment methods.     

基于张量优化的高动态范围微光相机设计与实现

针对空间低照度环境下,互补金属氧化物半导体(CMOS)相机成像视觉效果不佳的问题,基于张量优化的图像融合方法研制一款高动态范围的微光相机。分析基于科学互补金属氧化物半导体(sCMOS)图像传感器亮暗场双通道ADC的电路特性,利用同源双通道图像数据构建三阶特征张量,通过对特征张量的平行因子分析,以融合图像动态范围最优为评价函数,引入拉格朗日乘数法作为张量分解的优化算法,实现实时的高分辨力高动态范围成像。研制一款基于LTN4625的微光相机,并进行成像实验。仿真实验结果表明,相机实现了50帧/s,4 608×2 592像素的高分辨力高动态范围成像,图像动态范围从低增益数据的5.2 dB和高增益数据的11.4 dB提高到了54.7 dB。该设计是一种微弱光环境下动态响应范围高、成像效果好的微光相机设计方法。     

High dynamic range imaging with short- and long-exposures based on artificial remapping using multiscale exposure fusion

High dynamic range imaging (HDRI) is an excellent high-quality image acquisition technique, which can reflect real human visual characteristics from one (or several) captured low dynamic range (LDR) image. However, the input LDR image only provides partial information of the scene. Besides, in traditional HDRI methods that require multiple captured images as input, field of view errors can be induced, which will be difficult to apply it to the emerging image acquisition systems. Here, we propose a novel HDRI method that reconstructs an HDR image from only a pair of short- and long-exposure images based on artificial remapping using multi-scale exposure fusion. Firstly, we introduce a simulated exposure model called artificial remapping to synthesize a multi-exposure image sequence from the input LDR image pairs. Then, weighting maps of the sequence for fusion can be obtained according to the evaluation factors of contrast, saturation, as well as improved exposedness. Finally, we utilize the pyramid based multiscale exposure fusion framework to integrate them into an enhanced HDR image. Comparative experiments, fully implemented on some source images, have been demonstrated that better performance can be realized compared with some competing methods in qualitative and quantitative evaluation. Note that the operation of the proposed method is simple yet effective, which is easy to popularize. The method thus can be potentially applied to the emerging image acquisition systems where two images are captured simultaneously by two image sensors or by one image sensor with a pair of short- and long-exposure setting.     

一种基于交通视频的摄像机标定方法

介绍了一种线性模型下的摄像机标定方法。在获取交通视频的基础上,利用实际路面上的参照物和图像处理的基本知识抽象出交通视频中的像素行和路面实际距离之间的几何模型,对几何模型进行解析,得到视频图像上像素行和实际路面的距离映射关系。试验表明,该方法能够较好地实现图像上像素行到路面实际距离之间的转换。     

一种新型大动态范围CMOS图像传感器

提出了一种具有新型像素结构的大动态范围CMOS图像传感器,通过调整单个像素的积分时间来自适应不同的局部光照情况,从而有效提高动态范围。设计了一种低延时、低功耗、结构简单的新型pixel级电压比较器及基于可逆计数器的时间-电压编码电路。采用0.6μm DPDM标准数字CMOS工艺参数对大动态范围像素单元电路进行仿真,积分电容电压Vcint与光电流呈良好的线性关系,其动态范围可达126dB。在3.3V供电电压下,单个像元功耗为2.1μW。     

相机响应函数标定算法研究进展

高动态范围成像技术能够避免因为拍摄方向如逆光和曝光量的不同而使图像存在亮度和色差影响真实场景的信息采集,有利于复杂环境下获得更高的成像质量,因此被广泛应用于模式识别、智能交通系统、遥感遥测、军事监视侦察等众多领域,具有重要的研究价值。相机响应函数的标定是高动态范围成像技术的关键步骤,能够获得真实场景的辐照度与获得图像像素值之间的映射关系,从而通过该映射关系获得拍摄的真实场景的高动态范围图像。文章对目前现有的相机响应函数标定算法进行分类总结,可为相机响应函数标定算法的研究思路与方法提供借鉴。Abstract:关键词:Key words:     

用实时全息法配合摄像机研究固体火箭推进剂的燃烧过程

本文采用实时全息法与摄像机相结合的方法来研究固体火箭推进剂的燃烧过程，记录速度为２５帧／秒，曝光快门速度最高可达１／２０００秒。成功率高，条纹清晰，对固体火箭推进剂燃烧器燃烧过程取得了有用的结果。此方法对研究快速变化过程提供了一种简易有效的手段。     

大动态范围高精度激光透射率测量系统

透射率在光学领域中有着重要的用途,为了精确 的测量物体的透过率,本文基于自 相关检测原理设计了一套大动态范围高精度激光透射率测量系统,在分析噪声的基础上,计 算了最小可探测光功率,确定了测量的动态范围;同时分析计算了系统信噪比改善程度,最 终实现高精度测量。本文以635nm半导体激光器为光源,使用光电二极管为探测器,采用锁 相放大器对微弱探测信号的提取和对干扰信号的抑制,搭接了测量系统,通过分析计算得到 待测样品的透过率,并通过改变信号调制频率和锁相放大器的时间常数来观察其对信噪比影 响,最终选择调制信号频率在1000 Hz,锁相放大器时间常数为30ms 的情况下测量,实验表明 ,系统可测量透射率的范围为0.000%~100%,测量误差范围为1%。 对于其它波长或其它微弱信号构成的测量系统的动态范围和精度的分析具有借鉴意义。     

动态扩容视频存储分发系统设计

在带宽增速,互联网用户对视频内容的要求日趋增多的趋势下,本文描述了大规模视频存储分发的系统设计和实现.该系统设计的目标是把用户上传的视频重新编解码生成适合不同场景的不同格式视频文件,然后根据客户端支持的视频属性和网络带宽的实际情况,自动分发不同码流的视频文件到客户端,从而达到流畅访问视频的目的;对系统中的热门视频,系统通过算法结合缓存,实现同一视频文件在不同服务器间动态迁移,从而充分利用系统的计算能力,最终给用户提供更流畅的视频体验.     

基于AD9650的高速大动态范围数据采集系统设计

在高杂波环境下工作的雷达系统要求大的瞬时动态范围,才能实现对弱目标信号的录取,迫切需要设计实现高动态范围的高速数据采集系统。研究了ADC芯片选型、时钟设计和前端电路设计对数据采集系统动态范围的影响,基于AD9650设计实现了一个16 b,65 MSPS的高速数据采集系统,用于实现对高杂波环境下雷达回波信号的采集。     

基于动态视频的人脸识别技术研究

随着高科技的发展,人脸识别技术也在不断发展.如今市场上已经出现多种人脸识别技术.人脸识别技术作为一种生物特征识别的典型应用被应用到各个领域,如国防、司法、金融等,受到了社会的关注与认可.     

Transimpedance amplifier with a compression stage for wide dynamic range optical applications

A high dynamic input transimpedance amplifier was implemented in 130 nm CMOS technology. The proposed TIA is an inverter with a diode connected NMOS and a gate controlled PMOS loads which is cascode connected with the inverter. The square law compression NMOS increases the input photocurrent up to 10 mA. The TIA has an integrated input referred noise current of 135 nA, 227 MHz bandwidth. The TIA shows a transimpedance gain of 59 dBΩ and a 97 dB dynamic range. The TIA consumes 2.3 mA from 1.5 V voltage supply.     

高动态范围视频的多曝光图像序列快速融合

使用多次曝光法进行高动态范围视频获取时,需要将多幅低动态范围(LDR)图像进行快速融合,并满足视频融合系统的实时性要求。本文提出了一种改进的快速多分辨率塔形分解融合算法,在不降低原有算法融合质量的前提下极大减少计算量。算法分别从金字塔分解卷积核、高斯系数扩展插值方法、拉普拉斯系数融合规则、高斯系数融合规则等方面进行改进,简化了塔形分解、融合和重构过程。该方法应用在某运载火箭视频采集系统中,实验结果表明,该改进算法稳定性强,融合质量高,并极大地减少了计算量,运算速度提高了10倍以上,在TMS320DM642DSP上一帧512×512图像的融合时间约为8.9ms,满足25fps高动态范围视频融合的实时性要求。