Design And Implementation Of Target Contour Extraction Algorithm And Display And Control Software For Multi-band Passive Imaging

In the face of the coexistence of opportunities brought by today's global environment and threats brought by the rising terrorist forces,terahertz/millimeter wave passive detection imaging technology plays a very important role.All objects themselves radiate electromagnetic waves,and at the same time reflect electromagnetic waves in the environment.Terahertz and millimeter wave passive detection imaging technology is based on the difference of electromagnetic radiation energy between the target to be detected and the scene background in the corresponding frequency band.This technology has the advantages of high efficiency,high quality imaging and no radiation,and has important value in public security,anti-terrorism and anti-attack applications.Usually,due to the limitation of cost and component manufacturing process,the initial imaging results of THz/MMW detection imaging system are often low signal-to-noise ratio and blurred edge contour,which brings great difficulties for subsequent signal processing.In terahertz/millimeter wave passive images,the information contained in the target contour is of great significance to correct target detection and recognition.Therefore,it is of great significance to study practical and efficient target contour extraction algorithm.Display and control terminal is an important part of the imaging system.As the human-computer interaction unit and command,data receiving and receiving hub of the whole system,it is responsible for the control of servo scanning unit and signal acquisition unit,the monitoring of the status of the unit,and the real-time display and storage of the images collected by the system.The corresponding design process meets the basic requirements of display control,and the subsequent upgrade of functions should be considered in order to meet the various needs of the actual system.Relying on the actual scientific research projects,the main research contents of this thesis are as follows:1.The theoretical basis of terahertz and millimeter-wave passive imaging is studied.The radiation characteristics of the target and the penetration characteristics of the occluder are analyzed.The selection of the operating frequency of the system is analyzed and demonstrated.The basic working model of terahertz-band imaging system is summarized and introduced.2.Aiming at the characteristics of low signal-to-noise ratio and blurred edge of target in passive millimeter wave imaging,some preprocessing methods,such as spatial filtering,frequency filtering and anisotropic diffusion filtering,are studied and implemented.On this basis,combined with image segmentation theory,an improved region growing algorithm based on category and boundary pre-judgment is proposed to extract the contour of hidden objects,which has achieved good results in experimental verification.3.According to the overall scheme of the system in the actual project and the requirements of practical application,the selection of display and control terminal platform and development framework is carried out,and the functional modules,layout and development technology of display and control software are structured.4.The Graphical User Interface(GUI)of display and control software is developed,and its functions are verified by software simulation debugging and computer joint simulation debugging.The experimental results show that the indicators and functions meet the requirements of the project,and provide the possibility for subsequent upgrades.