Enhancement algorithm based on illumination adjustment for non-uniform illuminance video images in coal mine

Due to the environment of coal mine space is affected by grime, the images obtained by video surveillance have low illumination, non-uniform illuminance problems, and the existing algorithms cause color distortion or excessive enhancement in dealing with non-uniform illumination mine image, which is not conducive to the interpretation and application of images.With the actual images data, this paper proposed a new non-uniform image enhancement algorithm based on illumination adjustment combining with Guided Filtering and “S Curve” function, which may overcome the problems of the existing algorithms.By analyzing the characteristics of the video images, a multi-scale guide filtering, which can preserve the edges and corners, is adopted to get the illumination component.Then based on Retinex theory, the image is decomposed into an illuminance component and a reflection component.Regarding the non-uniform illumination, a new S-shape curve function is proposed to adjust the illuminance component.Considering the image has a relative low contrast, the contrast limited adaptive histogram is further used to enhance the contrast.Finally, a new image enhancement method is proposed with the detail enhancement coefficient and the illumination enhancement coefficient achieve a better enhancement performance of non-uniform images.Compared with the other four algorithms, this paper shows that the proposed algorithm is superior to the above algorithms both in subjective evaluation and objective evaluation.Finally, this algorithm can effectively enhance the overall image brightness and contrast, while avoiding excessive enhancement phenomenon of the bright region generated near the light, showing the superiority of the algorithm. © 2017, Editorial Office of Journal of China Coal Society. All right reserved.