图像梯度场双区间均衡化的细节增强

摘要

The technique of histogram equalization (HE) is widely used in the field of image enhancement,the method is introduced into the gradient field in this paper,so image details are distributed in each gray level uniformly.Moreover,the characteristics of the histogram of gradient magnitude are studied,according to the right-skewed distribution of gradient magnitude,the gradient field is equalized by two intervals.In terms of the threshold''s selection,numerical characteristics of frequency distribution are considered,two standards of the interval threshold are proposed,which can divide the gradient magnitude into the interval with low magnitude and the interval with high magnitude.On the process of the reconstruction of target gradient field,matrix transform method is proposed,which substitutes the traditional method "difference and iteration method",the proposed method can decrease the algorithm''s time complexity.The experimental results show that the method this paper proposed can make image details enhance effectively.%直方图均衡化技术已广泛地应用于图像增强中,本文将该方法引入梯度域,这样可以使图像细节均匀地分布在各灰度级上.进一步本文又研究了图像梯度幅值分布特点,根据梯度幅值的右偏分布特性,采取双区间分别对梯度场进行均衡化处理.在区间阈值选取上,本文结合频率分布的数字特征,提出了区间阈值的两个选取准则并将梯度幅值合理地分为小梯度区间和大梯度区间.在目标梯度场复原过程中,本文提出矩阵变换法替代传统的"微分迭代法",减小了算法的时间复杂度.实验结果表明本文算法可使图像细节得到有效地增强.