联合收割机作业情况远程视频监控系统设计

针对联合收割机作业现场偏远和作业信息滞后、监控调度不便等问题,提出一种基于嵌入式Linux和ARM硬件平台的视频监控系统方案.该系统选用Tegra K1作为信息处理核心,完整构建了嵌入式Linux系统,利用USB接口摄像头采集联合收割机各主要部位的工况视频数据,主要包括粮仓、脱粒滚筒、驾驶室、割台.设计了视频采集、显示程序,采用JPEG软件压缩方式、移植嵌入式视频服务器并通过移动无线网络将监控画面传输至远程监控中心.在试验测试中,该视频监控系统运行稳定,资源占用率低,拥有较好的实时性与清晰度,实现了对联合收割机作业情况的机载及远程视频监控.符合农机远程监控调度的需求,有利于农机管理信息化发展.     

基于ARM 和DSP 的无线视频监控系统

针对视频监控设备的应用需求,设计了一种基于ARM和DSP双核结构的无线视频监控系统。该系统采用CMOS摄像头完成现场图像的采集,在DM642内经JPEG2000压缩后,由S3C2410通过DSP的HPI口读取,并通过3G网络把视频数据传输到后台服务器。详细论述了系统的软、硬件的结构及其设计思想。     

RAW Image Reconstruction Using a Self-contained sRGB–JPEG Image with Small Memory Overhead

Most camera images are saved as 8-bit standard RGB (sRGB) compressed JPEGs. Even when JPEG compression is set to its highest quality, the encoded sRGB image has been significantly processed in terms of color and tone manipulation. This makes sRGB–JPEG images undesirable for many computer vision tasks that assume a direct relationship between pixel values and incoming light. For such applications, the RAW image format is preferred, as RAW represents a minimally processed, sensor-specific RGB image that is linear with respect to scene radiance. The drawback with RAW images, however, is that they require large amounts of storage and are not well-supported by many imaging applications. To address this issue, we present a method to encode the necessary data within an sRGB–JPEG image to reconstruct a high-quality RAW image. Our approach requires no calibration of the camera’s colorimetric properties and can reconstruct the original RAW to within 0.5% error with a small memory overhead for the additional data (e.g., 128 KB). More importantly, our output is a fully self-contained 100% compliant sRGB–JPEG file that can be used as-is, not affecting any existing image workflow—the RAW image data can be extracted when needed, or ignored otherwise. We detail our approach and show its effectiveness against competing strategies.     

嵌入式无线视频监控系统设计

本嵌入式无线视频监控系统采用高性能ARM9芯片作微处理器,通过嵌入式Linux采集USB摄像头视频数据,并将采集的视频数据帧经JPEG压缩;在ARM9芯片的控制下,通过2.4GHz无线发送/接收模块进行视频数据传输;无线接收端再将视频数据通过网络接口提交给视频应用服务端;最后由视频应用服务端将接收到的压缩数据帧重组、复合成视频图像,实现无线视频监控.     

基于多感兴趣区域无人值守变电站的图像监控

无线网络传输数据的带宽较窄,制约了无人值守变电站基于无线通信环境下图像监控系统的应用。而图像监控中,通常只对一个或几个区域感兴趣,为了适应目前的网络状况,应用了JPEG2000中感兴趣区域(ROI)编码技术,对感兴趣区域进行无损压缩,对其他区域进行有损压缩,明显地降低了图像的平均码率,使图像能够高效地传送给调度中心以便对现场设备的运行状态进行监控。实验结果表明,该方法很好地解决了压缩比和图像质量之间的矛盾,有效地缓解了传输数据量与网络带宽的矛盾,提高了图像的实时性传输。     

基于输入图像内容的比特率控制

在静止图像的压缩中 ,为得到固定大小的码流文件 ,有必要根据输入图像的特点 ,自适应地控制量化器的参数 ,从而控制输出压缩图像的比特率 .JPEG标准未给出比特率控制方法 ,而一些传统的比特率控制方法为专用的压缩解压缩系统设计 ,并不适用在于开放的基于交换格式的 JPEG压缩系统 .本文提出一种和 JPEG标准完全兼容的比特率控制算法 ,按照输入图像的活动性 ,计算相应的压缩质量因子 ,自适应地为每个 8× 8的块分配比特数 ,并且在熵编码时调整各块的比特数 ,适时启动块截除 ,保证压缩文件的大小不超过预先给定值 .本算法适用于存储容量有限的静止图像压缩的场合 ,可以保证存储规定帧数的压缩文件图像     

Categorisation and Retrieval of Scene Photographs from JPEG Compressed Database

Natural image categorisation and retrieval is the main challenge for image indexing. With the increase of available images and video databases, there is a real need to, first, organise the database automatically according to different semantic groups, and secondly, to take into account these large databases where most of the data is stored in a compressed form. The global distribution of orientation features is a very powerful tool to semantically organise the database into groups, such as outdoor urban scenes, indoor scenes, ‘closed’ landscapes (valleys, mountains, forests, etc.) and ‘open’ landscapes (deserts, fields, beaches, etc.). The constraint of a JPEG compressed database is completely integrated with an efficient implementation of an orientation estimator in the DCT (Discrete Cosinus Transform) domain. The proposed estimator is analysed from different points of view (accuracy and discrimination power). The images are then globally characterised by a set of a few parameters (two or three), allowing a fast scenes categorisation and organisation which is very robust to the quantisation effect, up to a quality factor of 10 in the JPEG format.     

Early width estimation of fragmented JPEG with corrupted header

In transformed and compressed domain fragmented files are very difficult to recover using conventional file recovery software. JPEG images are forensically important file format due to its popularity in a wide area of applications. In JPEG compression the header keeps important parameters that are required to decode the image back to pixel domain. In this paper the detection of width and height of an image from the JPEG stream is improved with less assumptions than previous papers. In the old approaches it was assumed that information about the image like Huffman table, Reset (RST) value and Quantization table were readily available for the techniques to work. However, in this paper the width is extracted from the quantized AC values that reduce the assumptions to just Huffman table.     

Compressed file length predicts search time and errors on visual displays

Search times and errors were recorded for targets (a gray triangle or trapezoid) in static marine radar, chart, and radar–chart overlay bitmap computer displays, and for targets in bitmap aerial photo displays. Lossless JPEG and ZIP compressed file lengths were obtained for each display. The two types of compressed file length were correlated and they predicted both the time to search each display and the number of search errors. Search time began increasing with increasing file size before errors began to increase. Compressed file size, an objective, easily obtained measure of display complexity, predicts both subjective complexity judgments (previous research) and objective search performance (these experiments). It is analogous to algorithmic complexity, a theoretical but impractical measure of bit string complexity. The data suggest that it may be possible to use the compressed file size measure to predict display performance in applied tasks.     

Advanced optical methods for safe image reproduction on automotive displays

Modern cars are equipped with camera monitor systems (CMSs), such as a backup camera or side-mirror replacement. These systems are expected to perform optimally and achieve high safety levels (ASIL). Currently, only digital data are supervised in CMSs and safety mechanisms for such systems are individually derived on a case-by-case basis which is not effective. This study proposes generic optical supervision for displays of automotive CMS. This paper introduces “light-to-light” (camera to display output) protection for both in-car CMS and remote operator monitors used in autonomous car fleet operation centers. The first method is based on photodiodes attached to the display to optically supervise, for instance, the speedometer of vehicles. By combining intensities of photodiodes with calibration data, we can compare the measured speed with the value from CAN (Controller Area Network) data. The second method that entails capturing the display content using a camera enables top safety levels for both in-car displays and remote operator monitors. This safeguarding was successfully verified by conventional image processing and artificial intelligence (AI)-based analysis methods. Our results demonstrate that AI methods allow a substantial reduction in the wireless transmission bandwidth from a car to a remote operator compared with conventional image processing.     

基于互联网技术的远程机器人控制器设计

采取利用互联网、IEEE802．11x无线局域网及移动电话网的方法，为轮式移动机器人设计具有视觉功能的远程无线控制器，实现远程无线控制轮式移动机器人的控制器软件、硬件的基本结构和设计方法。设计的两种嵌入式控制器分别在局域网和日本的3G无线移动电话网上进行了实验，在具有视觉功能的轮式移动机器人上实现了利用浏览器通过网络对轮式移动机器人进行远程无线操作控制，并在远程操作计算机上通过网络利用浏览器获取机器人实时视觉图像。     

基于GPRS网络的飞机除冰液加热监控系统

针对飞机除冰液加热,设计了一种基于GPRS(通用分组无线服务)网络的远程监控系统.它可以实现对设备的实时监控,及时有效地完成飞机地面除冰.该系统由上位机和下位机两部分组成:PLC作为下位机的控制系统,对执行机构进行控制输出,并且由A/D转换模块采集加热设备管道内的物理参数;远程控制中心作为上位机的监控系统,包括两种方式:一是利用数据服务中心作为远程控制中心,二是利用组态软件设计系统的操作界面作为远程控制中心.GPRS DTU(data transfer unit)通信模块通过GPRS网络完成与远程控制中心的无线通信,实现上位机与下位机之间的数据交互.     

JPEG compression for PACS.

In the medical field, especially in diagnostic radiology, there still remains controversy over how and whether or not to compress X-ray images for storage and transmission. The joint Photographic Expert Group (JPEG) standard which has recently been agreed upon is the very attractive technique to archive and to transport images in medical fields. This technique is based on 'lossy' compression of images, which can handle not only X-ray images but also full-colored images, and is suitable for introduction into picture archiving and communicating systems (PACS). The images can be handled after compression as quite small clusters of data. For example, a single 2000 x 2000 x 12 bits chest X-ray image which is an 8 Mbyte image compressed at a 10:1 ratio could retain virtually all the visible quality of the original version, and would take 100 s to transmit at 64 kbits/s using the Integrated Services Digital Network (ISDN, 800 kbytes compressed file, 8 kbytes/s transmission theoretically). An important factor in the design of this technique is that this format relies on no specific hardware or software if using JFIF (JPEG File interchange Format). Soon this algorithm will be able to run on any workstation or on any PC in the world. Highly compressed images may be unsuitable for diagnostic purposes. However, they may be sufficient for reference images which will be needed in clinical fields.     

基于H.264的嵌入式Web网络视频监控系统设计

针对传统的视频压缩技术不适合在恶劣的网络环境下应用的问题,提出了一种基于H.264的远程视频监控系统的设计方案。该系统将嵌入式技术、网络技术和视频编码技术结合在一起,嵌入式系统中的摄像头采集到的视频信号经H.264标准编码压缩后,通过系统内置的Web服务器实时地传递给远程监控端,从而实现了远程监控端的浏览器与嵌入式Web服务器之间的互联通信。测试结果表明,该系统的视频压缩率高、图像清晰、实时性强。     

无线传感器网络相机节点JPEG2000低功耗实现

无线传感器网络（WSNs）中,相机节点采集的图像数据量非常大,传输前需要对图像进行压缩。为了满足WSNs应用的低能耗、高图像质量需求,结合自行研制的基于DSP的相机节点,对JPEG2000图像压缩算法的低功耗实现问题进行了研究。对算法的小波变换、量化、编码等部分进行了改进,优化了其硬件实现方案。实验表明：通过一定的改进和优化,其实现过程中需要的存储量和实现时间大大降低,进而极大地降低节点能耗。     

基于嵌入式Linux的水位视频在线监测系统设计

为有效提高水位数据在线监测技术的自动化、智能化,针对当前传统水文仪器监测设备的微控制器(C51,MSP430及STM32等)主频低、智能性、鲁棒性差,以及水位监测数据的不精确、实时性差及成本高等问题,提出采用嵌入式Linux系统、图像处理及无线传输技术等实现水位数据在线自动监测。利用嵌入式Linux系统(Bootloader,Linux内核及Rootfs文件系统)定时控制网络摄像机获取高清图像,并在嵌入式Linux系统进行图像识别处理,将识别的水位信息和采集的图像通过无线模块传输至控制中心,以期实现水位视频在线监测与图像查询。该方法相比传统微控制器,具有监测水位数据处理速度更快、智能化程度更高、水位数据精度高、成本低实时性强等优点,并能够进一步推动水文仪器现代化建设发展。     

基于无线传感网络的爆炸场振动监测系统

爆炸场振动测试中节点分布范围广、数量多,对各测试节点的状态监控及全局管理难以有效实现,传统测试方案中节点部署后难以快速更改状态;针对上述问题,依据模块化、标准化和稳定性原则,设计了一种基于无线技术的振动监测系统;给出了爆炸场振动监测系统的基本功能单元,包括数据采集设备、无线组网设备;数据采集设备具有高精度采集、数据存储、高精度同步、定位定姿等功能;利用无线网桥技术构建了覆盖广域范围的无线网络,支持IEEE802.11 n/ac协议,实现了对远程分布式测试节点的集中管理、状态监控、数据传输,也可对指定测试节点的工作模式进行快速设置,以满足测试需求;测试节点的振动测量范围为0～10 g,室外1公里数据传输;通过模拟测试试验验证了系统的有效性,各项功能满足工程需要.     

煤田火灾无线远程监测预警系统设计

针对传统的煤田火区温度监测系统人工检测方式存在预测预报范围小,安装、维护工作量大,不能提供实时监测和预警等问题,设计了一种基于ZigBee技术、GPRS技术和Internet技术的煤田火灾远程监测预警系统。该系统通过设立在各个监测点的无线测温终端和网关将采集的温度信号发送到GPRS网络,经SGSN和GGSN接入Internet网络;上位机监测中心服务器再与Internet网络相连,以网页的形式显示监控界面,从而实现了煤田火区温度远程监测预警功能。现场试验结果表明,该系统解决了目前煤田火灾远程实时监测预警的难题,具有一定的实用性。     

双协议融合的WSNs温室环境监控系统设计

针对温室环境数据无线采集、视频监控及远程管理的需求,设计了一种基于无线传感器网络（ WSNs）的智能温室环境监控系统。系统采用ZigBee和WiFi融合通信技术组成智能网关,其中,ZigBee无线通信设备用于采集温室环境数据,WiFi通信设备用于无线视频传输和远程通信。所设计系统既避免了传统温室环境有线监控安装和维护的繁琐,同时解决了ZigBee WSNs传输速率较低、无线传输距离较近的缺点,温室环境监控功能得到拓展。经过测试验证,正常情况下网络丢包率小于1%,系统实现了温室环境远程监控管理的各项性能,具有良好的应用性和可扩展性。