Research On The Key Techniques For The Polarization Information Extraction And Application In The Target Detection

Compared with traditional imaging technology mainly do research on spectrum and intensity of target radiation,polarization imaging technology makes great use of polarization information.It can reflect surface feature,shape and roughness,so as to improve the accuracy of target detection and ground-object identification.Therefore,accurate extraction and effective utilization of polarization information will be the key point in polarization imaging technology.Under the research background of military camouflaged object detection,target recognition can be improved by establishing polarization measuring system in the paper.To distinguish artificial and camouflaged objects from complex background,this paper has carried out relevant research on measuring,extracting and fusing polarization information,as well as moving object detection.Main contents are presented as follows:1)Rapid measuring of polarization information in image:Polarization imaging device that can rapidly measure Stocks vector and Mueller matrix has been proposed in this paper.In Stocks image measuring system,due to inconformity of gray-to-gray response between channels in multi-channel polarization imaging system,gray scale response has been calibrated based on non-polarization character of sunlight under low scattering angle.In Mueller matrix image measuring system,a normalized calibrating method on Stokes vector of incident light has been proposed and the corresponding matrix has been constructed.Then Mueller matrix can be figured out rapidly with inverse operation of vector matrix.In this way,accuracy can been guaranteed and procedure can been simplified.2)Measurement of surface feature based on Mueller matrix:As optical feature of target's surface is the main factor to effect polarization state,Mueller matrix has been transformed into Mueller-Jones matrix by Coherency matrix,acquiring phase difference between p and s wave.Combining with Fresnel reflection formula,corresponding relation between optical constant and incident angle of target surface has been established.Afterwards,incident angle of each pixel from Mueller matrix image can be obtained according to the position of beam expander.Eventually,the paper has introduced the concept of Geometric-Optical model.With condition of diffuse reflection,linear relationship model among optical constant,incident angle and roughness of object surface is established.Therefore,optical constant deduced from this method can reflect surface feature and photoelectric character of target objectively.3)Technology of target enhancement based on polarization information:The application of elements in Mueller matrix is relatively simple at present,for depolarization elements are regarded as the only gist in most occasions.This paper has proposed a new parameter R(M)which synthesizes depolarized 'and polarized information through decomposing and trace operation of Mueller matrix.Taking R(M)as criterion,more detailed information can be revealed without losing principal part of target.As a result,polarization target enhancement method based on polarization information has been put forward in this paper.Fusion image reflecting polarization feature can be obtained by character extraction from orignal image,R(M)image and optical constant image with wavelet rules.Therefore target and background's information contained in R(M)and refractive images can be extracted effectively.In this way,information derived from original image can be increased,and recognition rate of target can be improved.4)Moving target detection based on extracting technology of polarization information:In the field of moving target detection,it is difficult to extract object from background with similar gray scale.Thus,this paper has put forward a method on moving target detection based on extracting technology of polarization information.Firstly,real time polarization imaging sequence of the scene has been required.Then,with polarization character,preprocessing has be carried out on single frame image so as to improve contrast ratio between object and background rapidly.Finally,combining with moving object detection,impurity of background can be settled and entire moving target can be extracted.This method has been proved with fairely detectivity and accuracy in moving target detction.Through analysis of polarization information,this paper has proposed new technologies on extraction of polarization information.It can be applied in measurment of surface feature,enhancement of target,detection of moving object and has made primary achievement.Results show that the research done above can provide a solid foundation for comprehensive application of polarization imaging system in the field of artificial target detection under natural background.