本文提出一种自适应图像增强算法。算法首先用最大值滤波和指数函数滤波平滑直方图，直方图局部最小值为波谷位置，波谷位置把输入图像动态范围分割为各个灰度区域。通过把各灰度区域适当映射到输出灰度区域，获得对比度增强。映射函数根据人类视觉特点进行设计，与灰度区域内均值，标准差及像素数目相关。实验结果显示本算法比其他几个算法达到了更好或相当的对比度增强效果。本算法无需参数调整即能适应各种类型图像，处理速度满足实时系统要求。 In this paper, we propose an adaptive image equalization algorithm that automatically enhances the contrast in an input image. The histogram is firstly smoothed through the max filter and exponential function filter. The troughs of the histogram, which are the local min positions, are used to partition the dynamic range of the image into gray-level intervals. The contrast equalized image is generated by transforming the pixels’ gray-levels in each input interval to the appropriate output gray-level interval according to the mean value, standard deviation and the cumulative distribution function of the input interval, based on human visual system. Experimental results show that the proposed algorithm produces better or comparably enhanced images than several state-of-the-art algorithms. The proposed algorithm is free of parameter setting and can be applied to a wide range of image types. The algorithm also can be used in real-time system.
