低照度下视频图像保细节直方图均衡化方法

摘要

Traditional histogram equalization method is realized by merging of the low frequency gray level.So the gray level that denotes the image details is often emerged overly and image detail information is lost.In this paper,an improved histogram equalization algorithm was put forward.When judging whether a gray level was to be merged with another,the weight coefficients with increased step were assigned to these low frequency gray levels according to their distance to the current gray level.Thus the excessive gray level merging was avoided.At the same time a nonlinear gray level mapping method was given to enhance the contrast of the original image.Experiment results show that the algorithm has obvious improvement.%传统的直方图均衡化方法是通过对直方图中像素出现频率低的灰度等级进行合并实现的,表征图像细节的灰度等级往往被过度合并而使图像细节信息丢失.为解决上述问题,提出了一种改进的直方图均衡化方法,在对两个灰度是否合并进行判断时,根据两灰度等级的距离分别赋与按照一定步长递增的权重系数,避免了灰度等级的过度合并,较好地保留了图像的细节.同时提出了一种非线性灰度级映射变换方法,提高了图像的对比度和整体亮度.实验结果表明,新算法具有明显的改进效果.