Polarization Defog Algorithm For Color Image Based On Median Filter And Global Search

The polarization characteristic of light contains abundant information of target and environment.Compared with traditional light intensity detection,polarization detection can obtain more information including degree of polarization,polarization direction and so on,which is helpful to improve the accuracy of target detection and recognition.Therefore,polarization detection technology has important applications in the field of ground object remote sensing,target detection,medical diagnosis,underwater detection and military identification.Polarization defog is used to obtain the scene image at different polarization angles by polarization imaging,and then uses the polarization defog algorithm to achieve the clarity of scene target.The traditional polarization defog algorithm is mainly suitable for gray image.Therefore,this thesis aimed at the application requirement of color image,based on the polarization defog of gray image,polarization defog algorithm for color images based on median filter and global search was proposed.The experimental result showed that the polarization color de-fogging algorithm could improve the imaging quality and had a good application prospect.The main work of this thesis is as follows:(1)Aiming at the problem that the particle size and concentration of scattered particles were difficult to be measured in practice,the method of using the equivalent representation of atmospheric visibility was studied,by establishing a mathematical model between the atmospheric visibility and particle concentration,using the atmospheric visibility to characterize optical thickness,and the equivalent analysis of atmospheric environment was realized.(2)Aiming at the inconsistency of atmospheric light intensity at different positions in the image,it was necessary to estimate the atmospheric light intensity of each point in the image.In this thesis,based on the median filter,a polarization defog algorithm for gray and color images was proposed,and the median filter was combined with the dark channel principle.The parameters of each pixel of the image were estimated,and finally the defog image was obtained according to the polarization defog model.(3)In order to solve the problem that the manual selection of the sky region leaded to inaccurate calculation of the polarization degree of atmospheric light,a color image polarization defog algorithm based on global search is implemented.The maximum and minimum intensity images were obtained by fitting curves,Using the global search algorithm to estimate the degree of polarization of atmospheric light,and obtaining the transmission rate based on the principle of dark channel,and the logarithmic transformation was used to enhance the defog image.The experimental result showed that the proposed algorithm could improve the image quality.