Abstract: Based on Brightness preserving Bi-Histogram Equalization (BBHE), an improved algorithm of gray image enhancement was proposed. An appropriate threshold, which was selected based on the entropy of the output image and the difference between the mean brightness of input and output images, was selected to cut the image, then BBHE and gray lever homogenization were performed respectively. This method makes the brightness mean error as small as possible and the entropy of output image as large as possible. Meanwhile, it can prevent over-enhancement. The experimental results prove that the new method has better performance on image enhancement.

Key words: histogram equalization, mean brightness, entropy, homogenization

摘要： 基于能保持亮度的双直方图均衡算法,提出了一种改进方法。根据输出图像的熵和输入输出图像的亮度均值差,选择合适的阈值将图像分割成两个子图,分别进行均衡和灰度均匀化处理,使得输出图像的亮度均值和原图接近的同时输出图像的熵尽可能大,并避免了过增强现象的出现。实验结果证明该处理方法能取得较好的增强效果。

关键词: 双直方图均衡, 亮度均值, 熵, 均匀化