Research On Underwater Image Restoration Method Based On Image Layer Separation

Underwater image is one of the important media to obtain underwater scene information,which plays an important role in underwater exploration,ocean research and other fields.However,when light propagates underwater,it will have a strong absorption and scattering effect with the water body,which leads to the degradation of underwater imaging quality and seriously limits the underwater visual range.Therefore,underwater imaging and restoration technology has great significance and practical value in underwater rescue,ocean exploration and marine target recognition.In this thesis,firstly aiming at the problem of removing the scattered light in the underwater image,we separate the scattered light in the image by using the idea of layering to realize the underwater image restoration and improve the quality of the underwater image;Secondly,aiming at the problem of poor image restoration effect caused by light source interference in underwater scene,an underwater image restoration method to suppress light source interference is proposed to reduce the influence of light source interference on image restoration.The main contents of this thesis are as follows:(1)Aiming at the problem of scattering light removal in underwater image,an underwater image restoration method based on image layered de scattering is proposed.The layered model of underwater image is established.The layer prior based on Gaussian mixture model is used to constrain the target layer and scattering layer and a simple and effective optimization method is used to optimize the solution to achieve the accurate separation of scattering light.In order to ensure the accuracy and effectiveness of prior information,Gaussian mixture model is used to model the target layer and scattering layer by counting the distribution characteristics of underwater image blocks.Experimental results show that the method can effectively reduce the influence of scattered light on the image and improve the image clarity.(2)Aiming at the problem that the interference of light source affects the image restoration in underwater scene,an underwater image restoration method is proposed to suppress the interference of light source.The underwater imaging model considering the interference of light source is established.The gradient distribution of the interference image with light source and the interference image without light source is used to separate the influence of light source.The global background light and underwater transmittance are estimated in the obtained underwater image to suppress the influence of light source,so as to reduce the influence of light source interference on parameter estimation.The experimental results show that the proposed underwater image restoration method can effectively reduce the influence of the light source on the image and significantly improve the visibility of the underwater scene.(3)Aiming at the effectiveness evaluation of the underwater image restoration method proposed in this thesis,the qualitative and quantitative experiments are carried out.This method is tested in underwater synthetic image data set,underwater natural image data set and laboratory simulation data.The objective quality evaluation index is used to quantitatively evaluate the restoration results of this method,and compared with other methods.The results of comparative analysis verify the effectiveness of the method in this thesis.