To solve the color cast and low contrast of underwater images caused by the effects of light absorption and scattering, we propose a novel underwater image enhancement method via bi-interval histogram equalization. The proposed method consists of three main parts: color correction, contrast enhancement, and multiscale fusion. First, the color cast is eliminated by automatic white balancing. Then, homomorphic filtering is adopted to decompose the image into high-frequency information and low-frequency information, the high-frequency information is enhanced by the gradient field bi-interval equalization which enhances the contrast and details of the image, and the low-frequency information is disposed via gamma correction for adjusting the exposure. Finally, we adopt a multiscale fusion strategy to fuse the high-frequency information, high-frequency after bi-interval equalization, and low-frequency information based on contrast, saturation, and exposure. Qualitative and quantitative performance evaluations demonstrate that the proposed method can effectively enhance the details and global contrast of the image and achieve better exposedness of the dark areas, which outperforms several state-of-the-art methods.

中文翻译：

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增强弱光水下图像的多尺度融合方法

为了解决由于光吸收和散射的影响而引起的水下图像的偏色和低对比度，我们提出了一种通过双间隔直方图均衡化的新型水下图像增强方法。所提出的方法包括三个主要部分：颜色校正，对比度增强和多尺度融合。首先，通过自动白平衡消除了偏色。然后，采用同态滤波将图像分解为高频信息和低频信息，通过梯度场双间隔均衡来增强高频信息，从而增强了图像的对比度和细节，频率信息通过伽玛校正来设置，以调整曝光。最后，我们采用多尺度融合策略融合高频信息，双间隔均衡后的高频信息，以及基于对比度，饱和度和曝光的低频信息。定性和定量性能评估表明，所提出的方法可以有效地增强图像的细节和整体对比度，并获得更好的暗区曝光度，这优于几种最新方法。