Research On Enhancement Algorithm Of Low Illumination Monitoring Image

Under low illumination conditions,monitoring images tend to be degraded,which can be divided into two situations.The first situation is that uneven illumination leads to obvious distribution of light and dark area of the image,with low pixel value in dark area,low contrast,and poor visual effect.Many existing image enhancement algorithms often have brightness distortion when enhancing such images,and there is often over-enhancement phenomenon in bright area while enhancing dark area.The original information of the enhanced image is lost.The second situation is caused by insufficient lighting.The overall image is dark,with low contrast,and the detail is not obvious,and the scene information is difficult to identify.The existing algorithms often have the problems of color distortion,brightness distortion,excessive image information loss,and poor image visual effect when enhancing such images.Therefore,it is particularly important to enhance low-illuminance images.For the first situation,an adaptive enhancement algorithm of uneven low-illuminance monitoring images based on OSTU is proposed in this paper.Firstly,the color space of the image is converted to HSV,the illuminance component of the V component is estimated by multi-scale guided filter algorithm,and enhance the reflection component.Then,two gamma curves are designed to adjust the different areas of illuminance component adaptively based on the V component threshold,which is calculated by OSTU.Additionally,integrate the adjusted illuminance component with the original illuminance component,and enhance the reflection component.Finally,combining the illuminance component and the reflection component,the processed V component is obtained.Compared with the algorithms proposed in related literature,the images enhanced by this algorithm have higher SSIM and PSNR values,while enhancing the dark area,it also avoids over-enhancement of the bright area of the image.The enhanced images are more in line with the visual characteristics of the human eye.For the second situation,an enhancement algorithm of uniform low-illuminance monitoring images based on S-curve is proposed by this paper.This algorithm is different from the former algorithm proposed in this paper in processing the V component.First,the Laplace algorithm is used to highlight the details and edges of the V component,after the illuminance component of the V component is estimated,an iteratively changing S-curve is used to continuously adjust the illuminance component,until the adjusted illuminance component and the enhanced reflection component are fused to obtain a V component whose brightness average value remains around 127.5.Compared with the algorithms proposed in related literature,the images enhanced by this algorithm have a higher average gradient,standard deviation,and information entropy.And it performs better in improving image clarity,enriching detailed information,improving contrast,and preventing color distortion.The enhanced images have a better visual effect.