Research On Short-Wave Infrared Defogging Technology Based On Polarization Under Marine Background

With the development of economy and the construction of maritime Silk Road,marine exploitation and maritime trade activities are becoming more and more frequent.Optical imaging system is playing an increasingly important role in marine related applications.However,in the marine environment,fog,haze and other bad weather will lead to low visibility of optical imaging system,which will bring great interference to optical detection in marine related fields.The mechanism of short-wave infrared(SWIR)imaging is similar to that of visible light imaging.The images obtained are rich in details,with strong ability to penetrate haze,long effective detection distance,and certain recognition and camouflage ability.Compared with visible light and long wave infrared,SWIR is more suitable for ocean related optical detection technology.In practical applications related to Marine optical detection,under the influence of fog,haze and other complex environments,problems such as low contrast and loss of detail blur will occur in SWIR images,which have a great impact on ship target recognition and Marine environment monitoring and other applications.Aiming at the above problems,this paper organically combines SWIR optical detection technology with polarization image de-fogging technology,and proposes a short-wave infrared polarization imaging de-fogging method based on range limit and atmospheric polarization limit.By more accurate estimation of atmospheric scattered light in two dimensions of polarization and range,the robustness of de-fogging is increased,and the detailed information of target objects can be effectively restored.At a deeper level,haze interference removal and clear target restoration are realized in complex marine environment.The main work contents and contributions of this paper are as follows:1.In view of the influence of changeable haze and other severe weather,complex lighting conditions and diversified scene targets on fog removal under the marine background,the following studies were carried out:(1)The composition and scattering characteristics of haze and other aerosol particles were explored in detail;(2)The reflection characteristics of fog field under different lighting environments are studied in detail.On the basis of atmospheric degradation model,the reflection characteristics of direct sunlight fog field model and nondirect sunlight fog field model are studied.(3)The characteristics of SWIR reflection and polarization of targets in diverse scenes under the ocean background are systematically studied.It provides theoretical support for the subsequent defogging technique of infrared polarization imaging.2.Due to the complex polarization characteristics of diverse scene objects in the marine background,atmospheric polarized light is seriously interfered by the polarization of the object’s reflected light.Because the basic polarization de-fogging algorithm mostly ignored the polarization influence of the object’s reflected light,the calculated atmospheric scattered light is large,and the image details are seriously lost after de-fogging.In order to solve this problem,a polarized limit fog removal method based on polarization degree and polarization angle difference is proposed in this paper.By using the difference of polarization degree and polarization angle between atmospheric scattering light and object reflection light in the region,the atmospheric scattering light interfered by some object reflection light is extracted.Then the atmospheric scattered light is obtained by refining the bottom envelope surface of the interfered atmospheric scattered light,and the fog removal effect is achieved.When there is an object with polarization degree or polarization angle different from the fog field in the local area,the polarization defogging effect is significant.The polarization degree of ocean area under haze is large,so this method has good effect on removing fog in marine area.3.There are two unsolved problems in the extreme polarization de-fogging method in the complex and changeable marine environment:(1)When the polarization characteristics of all the target objects in the region are close to the polarization characteristics of atmospheric light,the polarization de-fogging effect is poor;(2)The haze weather in marine environment is changeable,and the change of polarization characteristics of fog field will lead to the poor robustness of polarization imaging defogging method.To solve these two problems,a polarization imaging defogging method based on range limit and atmospheric polarization limit is proposed.In this method,the scattering light is calculated from two dimensions of polarization and range.Through the difference of reflection characteristics betw een objects and fog field in local area,the problem of unideal fog removal caused by insufficient difference in polarization characteristics between objects and fog field is solved to some extent.Because the reflection characteristic is the inherent property of the object,it is almost not affected by the scattering of haze.The organic combination of the two can estimate the local atmospheric scattered light accurately in two dimensions of polarization and range,and increase the robustness of fog removal.Through the method in this paper,while effectively dealing with haze,the image details of the target object can be truly restored.The image contrast,information entropy and average gradient are greatly improved,and better image restoration effect is obtained,with better de-fogging robustness.It provides an effective solution for optical detection in marine background.