Research On Underwater Image Enhancement And Restoration Algorithm

In recent years,marine resources have gradually become the strategic focus of the development of various countries in the world.If marine resources are reasonably exploited and utilized,it can alleviate the current situation of lack of resources on land.In the application of marine military,underwater target detection and tracking,the acquisition and enhancement of underwater optical image is the prerequisite for the study of underwater information.However,due to the absorption of light in underwater environment,forward scattering,back scattering,underwater imaging system is difficult to achieve satisfactory results.Underwater optical images often have many problems,such as color distortion,image blur,contrast reduction,detail loss and so on.Therefore,underwater image processing is of great significance.According to the causes of underwater image degradation,this paper studies the underwater image enhancement and restoration technology,mainly doing the following research work:(1)In this paper,an improved histogram equalization algorithm is proposed to correct the color of images in underwater environment.This method is based on a certain prior knowledge to correct the color of underwater image,and the effect of color balance of underwater image is remarkable.Compared with some classical white balance algorithms,this method is more suitable for underwater images.(2)Aiming at the problem of image blur and detail loss in water descent image,this paper presents an algorithm for image detail information enhancement based on fractional differential.This algorithm can not only enhance the details of the image,but also reduce the increase of underwater image noise.So we construct the proper fractional mask operator to perform fractional differential of underwater image.After the underwater image is magnified,it can be found that the pixel number is denser than that before processing.(3)This paper is inspired by the idea of guided filtering and image fusion.An underwater image restoration algorithm based on guided fusion is proposed,which uses the improved histogram equalization to enhance the contrast of the color balance image.The image enhanced by fractional differential details is used as the guide image to guide fusion.After the final guided fusion the image is more realistic and natural.(4)Because of the lack of research on underwater image quality evaluation methods,the quality evaluation algorithm of de-fogging algorithm in the air can not be directly applied to underwater images.Therefore,we introduce several methods suitable for underwater image quality evaluation,and apply them to the quality evaluation system of our algorithm.Through the verification and analysis of the experimental results,the algorithm proposed in this paper has a good enhancement effect on most underwater images.