基于非锐化掩模引导滤波的水下图像细节增强算法研究

针对水下图像对比度偏低，细节模糊的问题，本文提出基于非锐化掩模引导滤波的细节增强方法。首先由原始图像做引导图进行滤波得到细节层图像，并对细节层使用噪声检测的中值滤波去除斑点噪声；然后对原始图像进行基于均值滤波的非锐化掩模，得到锐化图像，并将锐化图像作为引导图对原始图像进行引导滤波，获取基础层图像；最后将滤波后的细节层进行增益后与引导滤波获取的基础层进行叠加，达到增强水下图像细节的目的。并通过信息熵、局部对比度和平均梯度3种客观评价指标对图像处理结果进行了对比分析，主观和客观测试结果表明，本文采用的算法能够有效提高图像对比度以及增强细节信息，有利于提高水下图像资料解释的准确性。

Research on underwater image detail enhancement based on unsharp mask guided filtering

To overcome the problem of the low contrast and blurred details of underwater images, we propose a method to enhance the details of underwater images based on unsharp mask guided filtering in this paper. Firstly, the original image is guided filtering to obtain a detail layer image, and the speckle noise in detail layer image is removed by the median filtering based on noise detection. Then the unsharp mask based on mean filtering is operated on the original image to obtain a sharpened image, which is used as guidance image to perform guided filtering on the original image, and the base layer image is obtained. It is magnified to boost the details so that the details of the output image are obtained. Finally, the filtered detail layer is magnified to boost the details, and the enhanced underwater image is the combination of the boosted detail layer and the base layer. The image processing results are compared and analyzed through three objective evaluation indexes: information entropy, local contrast and average gradient. Subjective and objective test results show that the proposed algorithm can effectively improve image contrast and detail information, which is beneficial to improve the accuracy of underwater image data interpretation.