基于暗原色先验原理的水下图像增强

针对水下光衰减和散射导致的图像严重降质问题和用传统方法进行水下图像增强产生色偏现象，提出一种新的水下图像增强方法。基于暗原色先验原理进行水下图像增强，用软抠图的方法对图像暗通道进行细化；在图像前0.1%最亮的像素点中，用中值滤波算法计算出这些像素点的中值，再计算这些像素点和与之对应的中值的差值，差值最小的像素点作为背景光的预估值，并用该像素点所在区域颜色饱和度方差来判断预估背景光的准确性；利用Retinex算法和图像各颜色通道的衰减系数比对增强后的图像进行颜色校正。实验表明，该方法能有效地去除水下图像中的雾色、校正图像色偏问题，进而提高图像对比度。

Underwater Image Enhancement Based on the Principle of Dark Channel Prior

In view of the serious degradation of the underwater images caused by underwater lightattenuation and scattering, a new method of underwater image enhancement is proposed in this paper.The new method based on the principle of dark channel prior conducts underwater imageenhancement and image thinning on dark channel by the method of soft matting. In the first 0.1%brightest pixels of the image, the medians of these pixels are calculated through the median filteringalgorithm. Then, the differences between these pixels and their corresponding medians are calculated,and the pixel of minimum difference is employed as an estimate of the background light. Theaccuracy of the estimated background light is judged by the color saturation variance of the regionaround the pixel. Afterwards, the Retinex algorithm and the ratio of attenuation coefficients for eachcolor channel are adopted to conduct color correcting for enhancement images. It is shown byexperiments that the proposed method can effectively dehaze the underwater images, correct the colorcast of images and further enhance the image contrast.