Liu Ke, Liang Yongquan
Opt Express. 2021 Mar 29;29(7):10321-10345. doi: 10.1364/OE.413164.
The attenuation (sum of absorption and scattering), which is caused by the dense and non-uniform medium, generally leads to problems of color degradation and detail loss in underwater imaging. In this study, we describe an underwater image enhancement method based on adaptive attenuation-curve prior. This method uses color channel transfer (CCT) to preprocess the underwater images, light smoothing, and wavelength-dependent attenuation to estimate water light and obtain the attenuation ratio between color channels, and estimates and refines the initial relative transmission of the channel. Additionally, the method calculates the attenuation factor and saturation constraints of the three color channels and generates an adjusted reverse saturation map (ARSM) to address uneven light intensity, after which the image is restored through water light and transmission estimation. Furthermore, we applied white balance fusion globally guided image filtering (G-GIF) technology to achieve color enhancement and edge detail preservation in the underwater images. Comparison experiments showed that the proposed method obtained better color and de-hazing effects, as well as clearer edge details, relative to current methods.
由密集且不均匀的介质引起的衰减（吸收和散射之和）通常会导致水下成像中的颜色退化和细节丢失问题。在本研究中，我们描述了一种基于自适应衰减曲线先验的水下图像增强方法。该方法使用颜色通道转移（CCT）对水下图像进行预处理，通过光平滑和波长相关衰减来估计水体光并获得颜色通道之间的衰减率，估计并细化通道的初始相对透射率。此外，该方法计算三个颜色通道的衰减因子和饱和度约束，并生成调整后的反向饱和度图（ARSM）以解决光强不均匀问题，之后通过水体光和透射率估计来恢复图像。此外，我们应用全局引导图像滤波（G-GIF）技术进行白平衡融合，以实现水下图像的颜色增强和边缘细节保留。对比实验表明，相对于当前方法，所提出的方法获得了更好的颜色和去雾效果，以及更清晰的边缘细节。
