基于颜色恒常性和多尺度小波的水下光学图像增强  

Underwater Optical Image Enhancement Based on Color Constancy and Multiscale Wavelet

作　　者：王晓琦 赵宣植 刘增力[1,2] Wang Xiaoqi;Zhao Xuanzhi;Liu Zengli(Faculty of Information Engineering and Automation,Kunming University of Science and Technology,Kunming 650500,Yunnan,China;Yunnan Key Laboratory of Artificial Intelligence,Kunming University of Science and Technology,Kunming 650500,Yunnan,China)

机构地区：[1]昆明理工大学信息工程与自动化学院,云南昆明650500 [2]昆明理工大学云南省人工智能重点实验室,云南昆明650500

出　　处：《激光与光电子学进展》2022年第16期32-42,共11页Laser & Optoelectronics Progress

基　　金：国家自然科学基金(61271007)。

摘　　要：针对水下光学图像出现的颜色衰减、表面模糊和光照不均匀等现象,提出了一种基于颜色恒常性和多尺度小波的水下光学图像增强算法。首先,采取灰度世界假设补偿衰减通道,利用颜色恒常性自适应调整图像全局亮度和对比度以有效校正色偏;其次,结合多尺度小波分解特性,采取基于形态学开运算改进的暗通道透射率移除低频雾霾现象,使用软阈值降低高频噪声;然后,利用二维伽马函数自适应校正不均匀光照,使用锐化提高边缘细节;最后,定义融合输入图像即伽马校正图像和锐化图像的权重图,并通过多尺度融合获得增强图像。实验结果表明,所提算法可有效平衡水下光学图像的色度和亮度,显著提高图像清晰度和细节信息;同时应用测试显示,该算法在特征匹配、弱光条件和边缘检测方面的表现出色。Aiming at the phenomenon of color attenuation,surface blur,and uneven illumination in underwater optical images,we proposed an underwater optical image enhancement algorithm based on color constancy and multiscale wavelet.First,we adopt the gray world assumption to compensate the attenuation channel and use the color constancy to adaptively adjust the global brightness and contrast of the image to effectively correct the color shift.Second,combined with the characteristics of multiscale wavelet decomposition,we adopt morphological open operation to improve the dark channel transmittance to remove the low-frequency haze phenomenon,and the soft threshold reduces the high-frequency noise.Then,a two-dimensional gamma function is used to adaptively correct the uneven illumination,and sharpening is used to improve the edge detail.Finally,the weight map of the fused input image is defined:gamma correction and sharpening images,and the enhanced image is obtained by multiscale fusion.The experimental results show that the proposed algorithm can effectively balance the chromaticity and brightness of underwater optical images and significantly improve image clarity and detail information.Additionally,application tests show that the algorithm performs well in feature matching,low-light conditions,and edge detection.

关 键 词：海洋光学 水下光学图像 图像增强 颜色恒常性 多尺度小波 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]