Abstract: To improve the visibility of fog-degraded images, a method for fog-degraded image clearness based on fuzzy logic was presented. The degraded image was mapped from the gray area to the fuzzy area，and then the fuzzy entropy was calculated to obtain the change rate of a pixel. By choosing the appropriate threshold for the fuzzy entropy，the image pixels were put into two categories，and then achieve different fuzzy feature enhancement operations. Experiment results show that this method can efficiently improve the degradation of image and enhance the clearness of image.

Key words: Fog-degraded images, ontrast enhancement, Fuzzy logic, Fuzzy entropy

摘要： 为了提高有雾图像的能见度，提出一种基于模糊逻辑增强雾天降质图像对比度的方法。该方法将整个有雾降质图像从灰度平面映射到模糊特征平面上，然后再利用模糊熵求出图像像素的灰度空间变化率，通过选取合适的阈值将图像像素点分成两大类，并在模糊特征增强变换时对它们实现不同的增强操作处理。实验结果表明：该方法能有效地改善雾天时图像的退化现象和提高图像的清晰度。

关键词: 雾天降质图像, 对比度增强, 模糊逻辑, 模糊熵