Research On Image Enhancement Algorithm Based On Retinex Theory

With the development of image processing and computer vision technology,the image has been inseparable from people's life.The image acquisition equipment can be seen everywhere in people's life.However,in the foggy day,the contrast,content and details of image obtained by sensors may be influenced by the outdoor environment.Thus researchers can not do any further research or analysis on these images which carry few useful information.In order to improve the quality of the images collected by the outdoor collection device,the dehazing measure is taken to deal with the foggy image,so that the image can be made clearer and more detailed information can be obtained.This is of great significance to further research or analysis on image.This main research content of this thesis is on the basis of analyzing the characteristics of foggy image,and improved the method which is based on the modified Retinex algorithm and the dark channel prior.Specific improvement content is as follows:In this thesis,adaptive guided filtering is introduced into the Retinex algorithm.Firstly,color space conversion is used to convert the fog image from RGB color space to HSI color space.Then,adaptive illumination is used to estimate the luminance component of image.The saturation component is stretched to obtain the final enhanced image.The experimental results show that the algorithm is better than the traditional algorithm of Retinex,and the fog image enhancement effect is better and the detail of the image is more obvious.This thesis mainly focuses on the shortcomings of the dark channel prior algorithm,and an improved algorithm for fog image enhancement based on dark channel prior is proposed.Firstly an adaptive correction transmissivity factor is introduced.Then compensates the problem of inaccurate estimation of the transmittance.Then the guided filter is used to replace the soft-method,which reduces the complexity of the algorithm.Lastly the use of gamma correction improves the problem of low image contrast after dehazing.Through the simulation and analysis,combined with the subjective and two objective angles,the average gradient of the image,information entropy and standard deviation of the experimental image quantitative analysis.Through the experimental verification,the method proposed in this thesis can get better fog enhancement effect,so that the image after the fog enhancement is more clear and natural.