Abstract: Aiming at the shortage that single scale Retinex algorithm has the halo phenomenon,noise amplification phenomenon and image graying,based on rotational symmetric bilateral filtering,this paper proposes a Retinex image enhancement algorithm.The illumination images are estimated with bilateral filtering invariant to rotation and their influence on visual effect is removed to get the reflecting images’ attributes,which can overcome the halo phenomenon effectively.Then threshold values are determined by Otsu threshold segmentation algorithm to judge the bright areas and dark areas of images,and the noise in these areas is removed to varying degrees by bilateral filtering,which can remove noise as well as reserve image details.The contrast in low contrast regions is enhanced with piecewise linear transformation,which can improve the insufficient about grey phenomenon of images.Experimental results show that the proposed algorithm can remove the halo phenomenon effectively,improve the noise amplification phenomenon significantly,get more abundant image information and enhance the contrast of images,which is better than the single scale Retinex algorithm and the Retinex algorithm based on bilateral filtering.

Key words: image enhancement, Retinex algorithm, rotational symmetric bilateral filtering, Otsu algorithm, image denoising, piecewise linear transformation

摘要： 针对单尺度Retinex算法存在光晕现象、噪声放大现象以及图像泛灰的不足,基于回转对称双边滤波,提出一种Retinex图像增强算法。采用回转对称双边滤波估计光照图像,并消除其对视觉效果的影响,得到反映图像本质属性的反射图像,有效去除光晕现象。运用Otsu阈值分割算法确定图像的阈值,并依此判断图像的亮、暗区域,采用双边滤波对这些区域进行不同程度的去噪处理,在去除噪声的同时能够较好地保留图像细节。采用分段线性变换增强低对比度区域的对比度,改善图像泛灰的不足。实验结果证明,与单尺度Retinex算法、基于双边滤波的Retinex算法相比,该算法能够有效去除光晕现象,明显改善噪声放大现象,获得更为丰富的图像信息,从而增强图像的对比度。

关键词: 图像增强, Retinex算法, 回转对称双边滤波, Otsu算法, 图像去噪, 分段线性变换

CLC Number: 

• TP301.6