采用双尺度图像分解的水下彩色图像增强  

Underwater color image enhancement based on two-scale image decomposition

作　　者：李健[1] 张显斗[1] 李熵飞 吴子朝[1] Li Jian;Zhang Xiandou;Li Shangfei;Wu Zizhao(School of Media and Design,Hangzhou Dianzi University,Hangzhou 310018,China)

机构地区：[1]杭州电子科技大学人文艺术与数字媒体学院,杭州310018

出　　处：《中国图象图形学报》2021年第4期787-795,共9页Journal of Image and Graphics

基　　金：国家自然科学基金项目(61675060)。

摘　　要：目的为解决水下图像的色偏和低对比度等问题,提出一种基于双尺度图像分解的水下彩色图像增强算法。方法通过基于均值和方差的对比度拉伸方法改善图像的色偏问题,并利用中值滤波降低红通道对比度拉伸后引入的噪声;采用双尺度图像分解绿通道图像补偿红通道图像细节;在处理后的红通道图像中引入原始图像红通道的真实细节与颜色。结果选取不同水下图像作为实验数据集,将本文方法与暗通道先验的方法、基于融合的方法、自动红通道恢复方法以及一种基于卷积神经网络深度学习的方法相比较,首先从主观视觉效果进行定性分析,然后通过不同评测指标进行定量分析。主观定性分析结果表明,提出的方法相比较其他方法能够更好地解决图像色偏和红色阴影问题;定量分析中,自然图像质量评价(natural image quality evaluation,NIQE)指标和信息熵(information entropy,IE)值较基于融合的方法和深度学习的方法分别提高了1.8%和13.6%,且水下图像质量评价指标(underwater image quality measurement method,UIQM)较其他方法更优。结论提出的双尺度图像分解方法利用水下图像成像特点解决图像色偏以及低对比度问题,具有良好的适应能力,同时算法复杂度低且鲁棒性较高,普遍适用于复杂的水下彩色图像增强。Objective Due to the complex and changeable underwater environment, when light enters a water body, it is affected by absorption and scattering, which leads to color cast, blur, and low contrast of underwater images. Water has different absorption capabilities for different light rays. As a result, the red channel information of the image is poorly preserved, making underwater imaging difficult. In order to solve the problems caused by light absorption in underwater images, existing scientific research has found that compared with the red and blue channels, the obtained green channel details of the underwater channel are best preserved, whereas the red channel details are poorly preserved. According to the characteristics of underwater imaging, the present study proposes an underwater color image enhancement method based on twoscale image decomposition. The method can effectively solve the problems of color cast and low contrast of the image and reduce the introduction of red shadow to obtain high-resolution underwater images.Method First, a contrast stretching method based on the gray world hypothesis is used. The method calculates the mean and mean square error of each channel independently and then uses a new normalization method using the mean and mean square error of each channel. In order to reduce the color cast problem of the image, a median filter is used to reduce the noise problem introduced by the red channel contrast stretch. Then, the two-scale image decomposition method is used to apply a large-scale mean filter to the red channel of the median filtered image and the green channel of the image after the contrast is stretched. Subsequently, the channel is divided into a large-scale base layer and a small-scale detail layer. While retaining the large-scale base layer of the red channel of the image, the small-scale detail layer of the green channel is introduced. Because the color and details of the red channel of the original image are equally important, the true details and colors of the red channe

关 键 词：水下图像 双尺度分解 均值滤波 细节补偿 色偏 红色阴影 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]