Polarization Imaging Detection Technique For Targets In Complex Underwater Environment

As the inherent property of light,polarization can reflect many physical features on the surface of an object and detect information that ordinary optical imaging cannot perceive,so it has received widespread attention.In recent years,polarization imaging detection technology has been applied in many fields,including atmospheric satellite remote sensing observation,military target detection,polar and deep-sea observation.As polarization detection has the unique advantages of suppressing cluttered backgrounds and obtaining effective information of the measured target,underwater polarization detection technology has developed rapidly.This technology can effectively suppress the scattered light of the medium and realize the restoration of the target scene.Based on the polarization difference imaging model,this thesis studies the polarization and image processing technology of underwater environment and mainly carries out the following three aspects of work:Firstly,based on the research work of underwater imaging and polarization detection technique,in order to achieve better restoration of the target scene image under strong underwater scattering environment,the thesis analyzes the underwater physical degradation model of polarization differential imaging,and improves the distortion of the traditional underwater polarization differential imaging model during image processing.The difference between the polarization degree of the scattered background and the measured target is used to highlight the measured target by the difference between the polarization degree of the local background scattering area and the polarization of the entire image,thereby obtaining the transmitted light radiation intensity of the target.At the same time,correction parameters are introduced to correct the intensity of the target transmitted light radiation,which effectively avoids the image distortion caused by the global parameters in the traditional underwater polarized differential imaging model and the local gray value is negative.From the perspective of the scattering environment of turbid media and the light source of underwater imaging,the synchronous imaging detection experiment of underwater targets based on the active illumination of linear polarized light is discussed and set.Secondly,the FD-1665 3CCD polarized imager was used for imaging,and skimmed milk was used to prepare turbid media reagent to simulate underwater turbid media environment.Experiments were performed to obtain polarized image data.Objective image quality evaluation parameters are introduced to compare the processing results.At the same time,in order to further verify the reliability of polarization imaging,different surface characteristic material targets were used for verification experiments.The results show that,for three different surface characteristics material targets,the improved model imaging effect has improved image contrast by 61%,40%,and 45% compared to the traditional polarization difference imaging model.Finally,from the point of difference between the uniformity of simulated water particles and the heterogeneity of natural water particles,the experiment is set up and the image data is processed.Different surface characteristic materials were selected for verification experiments.Comparing with the traditional polarization difference model,the restored image contrast of the improved model is improved by 50% and 62%respectively.In the experiment of artificial seawater with high salinity,the restored image contrast of the improved model was improved by 46%.The results show that the improved polarization differential imaging model can identify underwater objects more effectively,which indicates that the model has better stability and applicability.