Positioning beacon system using digital camera and LEDs

This paper is on a novel use of lighting or signaling devices constructed by light-emitting diodes (LEDs) as a positioning beacon. The idea is that the surface of the LED lighting device is divided into regions and used to show different visual patterns that are not noticeable by the human eye due to the high-frequency switching of the LEDs. A digital camera is used as a receiver to capture a sequence of images of the LED positioning beacon transmitter. Image-processing algorithms are used to decode the location code that is encoded in the visual patterns transmitted by the LED device. This idea can be applied to any LED traffic lights or signaling devices on the road and turn them into parts of a positioning beacon system. Such a system made up of high-brightness visible LEDs can provide the function of open-space wireless broadcasting of the positioning signal. The LED signaling method, transmission protocol, camera frame rate, LED flash rate, together with an implemented system and the experimental results, are presented in this paper.     

数码相机USB端口测试系统

随着表面贴装技术的发展,表面贴装零件的尺寸不断缩小,印刷电路板上零件密度增大,给印刷电路板及零件的测试带来困难.USB端口测试系统作为测试数码相机主板USB端口功能的工具,通过构建一个USB host来替代实际计算机.单片机AT89C52与USB芯片CH375能构建出USB host,满足生产线上大批量生产测试的需求.     

Toward an interactive poster using digital watermarking and a mobile phone camera

A method for embedding a watermark in print media, posters or other paper printouts and reading the watermark information blindly with a camera phone is proposed. A subtractive-additive embedding method is applied in which the message is coded with a directed periodic pattern. The message is detected and read by searching regularities in the autocorrelation function of a periodic signal. The robustness to disturbance occurring during printing process due to air interface and camera phone properties is ensured using noise reduction, modified JND model, enhanced peak detection with filtering and shaping and two-level coding of the message. The validity of the approach is proven with tests, and an application example of an interactive poster is examined.     

A secure digital camera based fingerprint verification system

Contemporary fingerprint system uses solid flat sensor which requires contact of the finger on a platen surface. This often results in several problems such as image deformation, durability weakening in the sensor, latent fingerprint issues which can lead to forgery and hygienic problems. On the other hand, biometric characteristics cannot be changed; therefore, the loss of privacy is permanent if they are ever compromised. Coupled with template protection mechanism, a touch-less fingerprint verification system is further provoked. In this issue, a secure end-to-end touch-less fingerprint verification system is presented. The fingerprint image captured with a digital camera is first pre-processed via the proposed pre-processing algorithm to reduce the problems appear in the image. Then, Multiple Random Projections-Support Vector Machine (MRP-SVM) is proposed to secure fingerprint template while improving system performance.     

基于FPGA的工业数字摄像机系统的设计

针对传统工业数字摄像机的灵活性差、实时性差等缺点,设计了一种基于FPGA的工业数字摄像机系统。将工业数字摄像机与FPGA结合起来,利用FPGA通过I2 C总线接口控制器控制图像传感器采集图像数据,然后将Bayer格式图像转化为RGB格式图像,通过调用Altera IP核DDRII SDRAM controller with ALTMEMPHY和FIFO存储器设计了DDR2SDRAM的接口,将图像数据缓存到DDR2存储器中,最后通过SPI总线接口在液晶屏上显示图像,可达到53帧/s图像的速度。系统代码共需约5 000个逻辑单元,3 704个寄存器,117个引脚。将设计代码下载到系统芯片中后,系统可以清晰显示所拍到的画面。设计结果表明,基于FPGA的工业数字摄像机设计灵活,易于移植,可实现高速图像采集和传输。     

数字视频监控中的远端摄像仪控制系统

以基于网络的数字视频监控为基础，论述了数字视频监控中远端摄像仪控制系统的工作原理、帧编码以及软件和硬件的实现方法。实际应用表明，系统具有操作灵活、误码率低的特点，可达到实时控制目的。     

Study of solder jet bumping process using high-speed digital camera

With the development of solder jet technology in the electronic packaging industry, the bumping process of a molten metal droplet, which determines the shape of the solder bump and is crucial for the performance of the device, has attracted great interests. The solder bumping process of a single molten micro-droplet by a solder jet was recorded using a high-speed digital camera with a frame rate of 100,000 frames per second. It was found that the surface ripples on the solder bump was caused by the interaction of the fluid flow and the heat transfer/solidification processes in the bumping process of a micro-droplet. A droplet was observed to rebound on a copper pad coated with a layer of organic solderability preservatives, which was suspected to decrease the interfacial heat transfer coefficient between the droplet and the pad lower than a minimal value, 4.07×10⁴ W/m² K, making the recoiling droplet rebound away.     

一种高帧频数字相机实时显示系统的研制

针对高帧频数字摄像机没有模拟输出,不能在普通的视频监视器上显示的问题,研究设计了一种用于高帧频数字摄像机的实时显示系统.利用FPGA实现相应的转换控制,实现方法是将数字摄像机输出的图像数据,首先进行Camera Link标准到TTL标准的转换,转换后的数据存储在FPGA中的双端口存储器中.然后对存储器中的图像数据按一定标准进行读取,并经过数/模转换产生模拟信号,叠加符合国家标准的视频同步信号,最后转换成为标准视频信号,可在普通监视器上显示图像.另外变换后的信号有利于远距离传输,并且可使系统调光时采用普通视频信号检测.采用此种小型系统能使非标准摄像机应用得到进一步扩展.     

基于DSP的嵌入式数字摄像夜间能见度测量系统

数字摄像夜间能见度仪的关键技术之一在于高速、实时地处理CCD采集的目标光源和黑体的图像信息。设计了一种基于TMS320DM642的小型化、便携嵌入式能见度测量系统,从硬件和软件上给于实现,并将其应用到数字摄像夜间能见度测量中。利用CCD采集25帧/s的PAL制视频流,数字化后送入DSP处理器,通过DSP实现目标光源与黑体的图像分割与定位算法,完成数字摄像夜间能见度的测量。实验结果表明设计的嵌入式系统能较好完成夜间能见度的测量。     

Practical vignetting correction method for digital camera with measurement of surface luminance distribution

Vignetting refers to the fall-off pixel intensity from the centre towards the edges of the image. This effect is undesirable in image processing and analysis. In the literature, the most commonly used methods of vignetting correction assume radial characteristic of vignetting. In the case of camera lens systems with non-radial vignetting, such approach leads to insufficient correction. Additionally, the majority of vignetting correction methods need a reference image acquired from a uniformly illuminated scene, what can be difficult to achieve. In this paper, we propose a new method of vignetting correction based on the local parabolic model of non-radial vignetting and compensation of non-uniformity of scene luminance. The new method was tested on camera lens system with non-radial vignetting and non-uniformly illuminated scene. In these conditions, the proposed method gave the best correction results among the tested methods.     

A novel digital predistorter technique using an adaptive neuro-fuzzy inference system

This letter presents a novel digital predistorter technique using an adaptive neuro-fuzzy inference system (ANFIS). The proposed approach employs real-time input and output signals of a nonlinear power amplifier as inputs to the ANFIS, so as to approximate the inverse functions of the power amplifier. The antecedent and consequent parameters of the FIS constructed by the ANFIS are tuned using backpropagation and least squares algorithms. Simulation shows that this novel technique has improved the linearity of a WCDMA signal by a further 4 dBc compared to a conventional look-up table (secant) approach. Moreover, this proposed technique is capable of adapting to instantaneous variation in the power amplifier response through time, which is a topic often omitted by researchers in this area.     

TNRAC: a system for tracking multiple moving non-rigid objects using an active camera

This paper presents an enhanced method for detecting and tracking moving objects from an active camera image sequence using active contour models. Such enhancements are: (1) Using best block matching instead of the conventional block matching technique to locate the promising feature points in the current frame. (2) Developing a new algorithm for rejecting bad feature points that affect negatively the background compensation process. (3) Applying a modified region growing and labeling algorithm to extract moving objects then applying active contour models around these moving objects in order to take into account the object inside this contour. Various factors are studied to measure the system performance and limitations. A comparison of TNRAC and the conventional approach is conducted using both rigid and non-rigid objects in both indoor and outdoor scenes.     

UAV载特轻小型组合宽角数字相机拼接模型

针对无人飞行器小负载的需求,设计了具有自检校功能的特轻小型四组合宽角数字相机,克服了数码相机像幅小,基线短的缺点;提出了一种基于软式的稳定平台的解决方法,实现了无稳定平台的正直航空摄影测量,满足了高精度、高效率的大比例尺低空摄影测量应用,解决了城市复杂建筑物多面纹理的获取问题。测图精度检测结果表明:相机相对自检校有效纠正了航摄过程中的机械变形,满足了影像拼接的几何精度,使用该组合宽角数码相机影像资料测制的1:1000比例尺地形图可满足精度要求,优于规范规定的限差。     

Continuous digital zooming of asymmetric dual camera images using registration and variational image restoration

This paper presents a theoretical basis to realize a high-quality digital zooming using two camera modules with different focal lengths. First, we describe an image degradation model of the asymmetric dual camera system to analyze the characteristic of the wide- and tele-view images. In an asymmetric dual camera system, we assume that the shorter focal length module produces the wide-view image with the low-resolution. On the other hand, the longer focal length module produces the tele-view image by an optical zooming. To reconstruct a wide-view image of a continuous digital zooming, the proposed method first estimates the point spread function (PSF) between the wide- and tele-view images. Next, the proposed method performs variational-based image restoration using the estimated PSF. In addition, since the tele-view image inserted into appropriate region of the wide-view image, the proposed method can provide significantly improved wide-view image.

     

Optical waveguide directional coupler measurements using amicrocomputer-assisted TV camera system

Characterization of optical waveguide directional couplers using a microcomputer-assisted TV camera system is reported. A fluorescent technique is employed to visualize wave propagation in the optical waveguides, which exhibit small scattering. The method is simple and reproducible, and can be used to estimate waveguide losses and evaluate various optical devices such as waveguide lenses and waveguide interferometers on substrates. As an example of its application, parallel and nonparallel dual-chamber directional couplers and parallel triple-channel directional couplers are measured. Power transfer between the coupled channel waveguides is observed clearly, and coupling coefficients of the couplers are obtained nondestructively. The measured performance of the couplers is in good agreement with that predicted by coupled-mode analysis     

Video camera system using liquid-crystal polarizing filter toreduce reflected light

We have been developed a video camera system using an electrically-controllable liquid crystal polarizing filter for television program production, which can quickly reduce undesirable reflected light from a window pane or watery surface, by automatically judging the polarization state of incident light from the change in video signal intensity. More than 80% of linearly-polarized incident light is removable by this method for all incident polarization angles. The time required for detecting and reducing reflected light is approximately 0.3s in our system. The drastic reduction of polarized light reflected from glass and watery surfaces was demonstrated, and object images obscured by bright reflected light were clearly captured in an instant     

A knowledge-based vision system for detecting land changes at urbanfringes

An experimental vision system for remote sensing land use/cover change detection is presented. The system was designed to monitor the processes of urban development. The design strategy, system structure, and image analysis sequence are addressed. Some experimental results are presented. Techniques are described in detail which were aimed at addressing the key aspects to constructing a knowledge-based vision system: preprocessing, spatial representation and manipulation, and incorporating ancillary data     

Adaptive optimally switched control system using digital techniques

This letter describes work currently being carried out in the field of adaptive optimally switched control systems using digital techniques. Basically the actual phase-plane trajectory of a second-order system is compared with the optimum trajectory, to obtain the correct switching point for minimum response time. A novel method is used to avoid measurement or computation of error rate, and some conclusions are given.     

先进微波探测器资料反演地表微波辐射率试验

利用美国环境卫星A型先进微波探测器AMSU-A资料反演中国陆地区域地表微波辐射率.通过辐射传输正演模拟,提出了AMSU-A窗区通道反演地表微波辐射率的指数分析方法.利用模拟数据对比了指数分析方法和以往通道亮温组合方法.结果表明:对于地表比较干燥的地区,指教分析的反演结果略优于通道亮温组合的反演结果.在此基础上利用IGBP(International Geosphere-Biosphere Program)的地表分类数据,提取AMSU-A像元裸土组分的面积百分比信息,并进一步应用于AMSU-A像元裸土组分地表微波辐射率的反演试验,提高了反演精度,并可进一步应用于区域地表湿度信息提取和大气参数反演,以及AMSU-A窗区通道陆地区域遥感信息在数值预报模式中的同化应用.     

FSK demodulation using an adaptive recursive digital filter

A second-order adaptive recursive digital filter is used for frequency-shift keying (FSK) demodulation. Explicit formulas are derived for the noise variance in the frequency detector, and optimum transmitter carrier frequencies and detector threshold frequencies are calculated. A formula for the adaptation time is derived and the error probability is found. Computer simulations verify the derived results