Image Quality Evaluation in Security Imaging Systems

The subjective image quality of image or video information is a crucial item in security imaging systems. During the last five years our lab has tested and verified various approaches to the image compression for security purposes and the evaluation of subjective image quality. In the paper we discuss selected important facts related to the subjective image quality evaluation and we present some anomalous experimental behavior of image compression techniques. An object-defined approach is investigated and advantageous characteristics of chosen methods are deployed to achieve the optimal performance of the surveillance video coder. Among others, we propose to use the artificial neural network (ANN) to predict resulting image quality rating scores. The proposed quality assessment model has been trained and tested using a set of grayscale images distorted by selected image compression algorithms     

Detecting small moving objects using temporal hypothesis testing

This paper addresses the problem of detecting small, moving, low amplitude objects in image sequences that also contain moving nuisance objects and background noise. We formulate this problem in the context of a hypothesis testing procedure on individual pixel temporal profiles, leading to a computationally efficient statistical test. The technique assumes we have reasonable deterministic and statistical models for the temporal behavior of the background noise, target, and clutter, on a single pixel basis. Based on these models we develop a generalized likelihood ratio test (GLRT) and perfect measurement performance analysis, and present the resulting decision rule. We also propose a parameter estimation technique and compare its performance to the Cramer Rao bound (CRB). We demonstrate the effectiveness of the technique by applying the resulting algorithm to real world infrared (IR) image sequences containing targets of opportunity. The approach could also be applicable to other image sequence processing scenarios, using acquisition systems besides IR imaging, such as detection of small moving objects or structures in a biomedical or biological imaging scenario, or the detection of satellites, meteors or other celestial bodies in night sky imagery acquired using a telescope     

微振动影响下的TDICCD相机图像复原方法

随着遥感卫星成像分辨率的不断提高,微振动对空间相机成像质量的影响已不能忽视。本文主要针对微振动影响下的时间延迟积分电荷耦合器件（TDICCD）图像的复原方法进行了研究。首先,结合成像器件与目标存在相对运动时的曝光成像规律和TDICCD相机成像原理,建立了微振动下TDICCD相机的成像模型,并进行了仿真得到退化图像。然后,对面阵图像复原方法进行了介绍。最后,将面阵复原方法改进推广至TDICCD图像复原,提出了一种微振动影响下的TDICCD相机图像复原方法,并进行了仿真。恢复图像各指标均有一定提升,验证了方法的有效性。     

大视场紧凑型仿生复眼成像系统研究

针对视觉导航系统对小型化、超分辨成像和近程立体视觉的需求,研究了一种基于微端面光纤面板的大视场紧凑型仿生复眼成像系统。利用视轴发散的微小型透镜组进行大视场成像,并以切削斜端面的光纤面板进行图像传输,将大面阵(5120×5120像素)CMOS相机与光纤面板后端面直接耦合实现图像输出,可实现9个视场部分重叠子孔径图像同步实时输出和采集。在实时化拼接处理中,利用CUDA并行加速方法进行图像拼接,单帧的拼接耗时小于30ms。视场部分重叠复眼成像模式还可配置偏振片或滤光片构成全偏振或多光谱成像,在天空偏振光导航、无人机紧急避障、弹载侦察、近程引信以及水下无人潜航器导航等领域具有广泛的应用前景。     

Limitations on SAR Image Area Due to Motion through Resolution Cells

Range-Doppler imaging systems are degraded by the motion of an object through its resolution cells during image formation. Given the range resolution dR, the cross-range (azimuth) resolution dA, and the wavelength ?, the image's range extent DR and cross-range extent DA must be constrained by ?DR ? 4d2A; ?DA ? 4dAdR to avoid significant image degradation. By implication, we can image a rectangular area A ? DADR. We show that, in general, the acceptable image area is a parallelogram which becomes a rectangle only in the special case of unsquinted, broadside operation. Furthermore, the actual useful image area within a rectangular map of range extent DR and crossrange extent DA decreases as the squint angle measured from broadside increases.     

Multi-view space object recognition and pose estimation based on kernel regression

The application of high-performance imaging sensors in space-based space surveillance systems makes it possible to recognize space objects and estimate their poses using vision-based methods. In this paper, we proposed a kernel regression-based method for joint multi-view space object recognition and pose estimation. We built a new simulated satellite image dataset named BUAA-SID 1.5 to test our method using different image representations. We evaluated our method for recognition-only tasks, pose estimation-only tasks, and joint recognition and pose estimation tasks. Experimental results show that our method outperforms the state-of-the-arts in space object recognition, and can recognize space objects and estimate their poses effectively and robustly against noise and lighting conditions.     

Adaptive nulling of SAR sidelobe discretes

By using adaptive subarrays for crossrange imaging we have developed a computationally simple method that removes any image degradation caused by strong, discrete clutter located in the crossrange sidelobes of a synthetic aperture radar (SAR) image. The procedure is based on the minimization of the mean interference power with the constraint that the image of a desired scatterer is undistorted. The applicability of the approach has been illustrated by simulation     

超分辨距离-多普勒成像的动态优化方法

提出了超分辨距离多普勒成像的动态优化方法,基本思想是利用正则化图像重建方法及动态优化算法求出雷达目标反射率的最小二乘估计。还利用FFT大大提高了动态优化算法的计算效率。用B-52飞机缩比金属模型微波暗室转台实验数据和Boeing-727飞机外场实测数据进行成像的初步结果表明,采用超分辨成像方法可以获得更高的图像分辨力;或用较小的信号带宽和成像总转角,可以获得相同质量的图像。进一步研究发现,如果能充分利用成像区域中更多的先验信息,动态优化方法可望能提供更好的分辨性能。     

基于飞行器图像的目标跟踪方法研究

提出了一种利用飞行器图像进行目标跟踪的方法，建立了飞行器图像跟踪系统。该系统利用一种云台控制算法搜索飞行器的图像，通过对飞行器图像的边缘检测、图像中心点提取等处理，实现了飞行器图像定位。理论计算和实际应用表明，该系统可以对低马赫数和高马赫数飞行器进行图像跟踪。     

Feature enhancement and ATR performance using nonquadratic optimization-based SAR imaging

We present an evaluation of the impact of a recently proposed synthetic aperture radar (SAR) imaging technique on feature enhancement and automatic target recognition (ATR) performance. This image formation technique is based on nonquadratic optimization, and the images it produces appear to exhibit enhanced features. We quantify such feature enhancement through a number of criteria. The findings of our analysis indicate that the new feature-enhanced SAR image formation method provides images with higher resolution of scatterers, and better separability of different regions as compared with conventional SAR images. We also provide an ATR-based evaluation. We run recognition experiments using conventional and feature-enhanced SAR images of military targets, with three different classifiers. The first classifier is template based. The second classifier makes a decision through a likelihood test, based on Gaussian models for reflectivities. The third classifier is based on extracted locations of the dominant target scatterers. The experimental results demonstrate that the new feature-enhanced SAR imaging method can improve the recognition performance, especially in scenarios involving reduced data quality or quantity.     

微动目标跟踪成像一体化的雷达资源优化调度算法

相控阵雷达可以同时担负搜索、跟踪、识别与成像等多种雷达任务。为了提高雷达对战场环境的感知能力并减轻雷达资源分配的冲突,提出一种微动目标跟踪成像一体化的雷达资源优化调度算法。该算法建立了包含微动目标成像任务的雷达优化调度模型并利用启发式算法求解,利用跟踪脉冲与调度剩余的空闲时间资源,动态地构造感知矩阵并采用正交匹配追踪（OMP）算法对微动目标进行特征提取并成像。仿真结果表明：该算法可以实现稀疏孔径条件下的微动目标成像,并具有良好的鲁棒性,同时进一步提高了雷达系统的资源利用率。     

基于三维激光成像系统的相机标定方法

三维激光成像系统中点云数据与影像数据的融合可以对被扫描物体赋予真彩色.为了获得点云数据与影像数据良好的融合效果,就需要精确的确定载体坐标系与相机坐标系之间的关系.本文针对三维激光成像系统点云模型真彩色处理方法进行研究,提出了一种基于三维激光成像系统的相机标定方法.通过对相机坐标系的标定,建立点云数据与影像数据之间的数学模型.实验结果显示,采用所提出的方法,能够使得三维立体点云数据与影像数据精确融合.最终得到被扫描目标的真彩色3D模型.     

多光谱手指静脉成像与采集系统设计

多光谱手指静脉图像信息采集对提高手指静脉识别性能具有重要意义,从活体组织的不同介质对不同波长的入射光有不同的散射和吸收性能这一角度出发,建立了多光谱手指静脉成像采集系统。重点介绍基于数码管控制芯片的多波段光源控制电路而搭建的硬件系统及设计的相应软件系统。该系统不仅解决了多模态手指静脉图像成像与采集的一些基本问题,而且为多光谱手指静脉识别奠定了数据基础和实验环境。这对促进手指静脉识别技术的发展具有重要意义。     

Superiority of canards in homing missiles

We suggest a first-order model to distinguish between nose control (canards) and tail control. We present optimal guidance strategies and demonstrate the superiority of nose control. This simple model enables us to develop simple and robust guidance strategies based on three approaches: unconstrained optimal control, constrained optimal control, and constrained differential games. It turns out that nose control requires low gain and is capable of forcing small miss distance in the presence of a maneuvering target.     

飞行力学在图像制导导弹设计中的应用

为满足作战需要 ,改善导弹的总体性能 ,又有利于降低研制成本 ,对图像制导导弹的导引头最大跟踪角速度、极限框架角、搜索方案以及导弹的速度方案 ,进行了分析设计。以此为例 ,对飞行力学在导弹总体与分系统设计中的应用进行了说明。研究结果表明 :飞行力学是协调导弹总体与各分系统之间关系的重要手段 ,在导弹总体和各分系统的设计过程中 ,积极主动地应用飞行力学进行综合设计 ,可获得最佳的总体性能。     

浮法玻璃均匀性的光学检测方法

在浮法玻璃的生产中,均匀性的检测与控制对于玻璃的质量保证至关重要.本文给出了一种可有效用于浮法玻璃均匀性检测的光学方法.实验结果表明,该方法采用平行偏振光成像系统和CCD图像采集与处理技术,可以清楚地获得平板玻璃样品侧向均匀性分布的光学图像,并能对图像的灰度分布进行定量分析,从而可为玻璃的质量评价和工艺控制提供可靠的依据.     

海冰热力模式抛物型分布参数系统区域辨识模型及性质

根据北极海冰的热力学性质,建立了北极海冰热力模式时变区域抛物型分布参数系统及关于雪层与冰层的厚度辨识模型(即最优控制模型),论述了该系统解的存在唯一性及最优控制的必要性条件。     

The Progress of the Taiwan Oscillation Network Project

We describe the present status of the project of the Taiwan Oscillation Network (TON) and discuss a scientific result using the TON data. The TON is a ground-based network to measure solar intensity oscillations for the study of the solar interior. Four telescopes have been installed in appropriate longitudes around the world. The TON telescopes take K-line full-disk solar images of diameter 1000 pixels at a rate of one image per minute. The data has been collected since October of 1993. The TON high-spatial-resolution data are specially suitable for the study of local properties of the Sun. In 1997 we developed a new method, acoustic imaging, to construct the acoustic signals inside the Sun with the acoustic signals measured at the solar surface. From the constructed signals, we can form intensity map and phase-shift map of an active region at various depths. The direct link between these maps and the subsurface wave-speed perturbation suffers from the poor vertical resolution of acoustic imaging. Recently an inversion method has been developed to invert the measured phase travel time perturbation to estimate the distribution of wave-speed perturbation based on the ray approximation. This technique of acoustic imaging has been used to image the far-side of the Sun that could provides information on space weather prediction. The TON Team includes: Antonio Jimenez (Instituto Astrofisica de Canarias, Spain); Guoxiang Ai and Honqi Zhang (Huairou Solar Observing Station, P.R.C.); Philip Goode and William Marquette (Big Bear Solar Observatory, U.S.A.); Shuhrat Ehgamberdiev and Oleg Ladenkov (Ulugh Beg Astronomical Institute, Uzbekistan) This revised version was published online in August 2006 with corrections to the Cover Date.     

无人直升机视觉着陆中的运动状态估计算法

对无人直升机(UH)视觉着陆中基于视觉图像处理的运动状态估计问题进行了研究。介绍了视觉着陆原理,分析了运动估计、特征图像处理与着陆控制间的关系,推导并建立了UH相对着陆平台位姿估计算法、线速度与角速度估计算法。相邻两帧图像对应特征点像点位置为位姿估计算法提供数据,一帧图像特征点像点位置及其对应像点平移速度为线速度与角速度估计算法提供数据。利用UH着陆控制仿真数据模拟UH着陆运动过程中像点位置及其对应平移速度的视觉图像处理结果。仿真验证了运动状态估计算法,结果表明所提出的运动状态估计算法能有效地利用视觉图像处理结果数据估计出UH的位置、姿态、线速度和角速度。     

激光图像融合算法

为了有效提高激光强度图像的质量,使其能够更好地与其他多源图像匹配,提出了一种激光强度图像与距离图像融合的方法.该方法首先分析了激光强度图像与距离图像不同类型像素点之间局部统计信息的差异,然后利用Ostu算法和模糊最小误差阈值算法求出强度像和距离像的局部统计信息的全局阈值和最佳阈值,最后将这些阈值作为融合参数,按照一定的融合规则,将强度像与距离像进行融合.仿真实验表明:与单纯的滤波算法相比,该融合算法在控制激光散斑噪声的同时,通过融合不同源图像的互补信息,达到提高激光强度图像的各方面性能的目的.