Abstract: The new image scrambling degree evaluation method based on fuzzy divergence theory is proposed.This paper firstly constructs the fuzzy set of two order neighbor system of image pixel and defines its membership，then the fuzzy divergence between the fuzzy set of two order neighbor system and its fuzzy complement set is computed，last the evaluation function of image scrambling degree is constructed by means of the fuzzy divergence of primary image and scrambled image.Experimental results show that the proposed method is effective to describe the relation between the scrambling effect and the number of iterations in the scrambling techniques，which largely consists with human vision.For different images，when some transformation is used，this evaluation method can reflect to some extent the scrambling effects in each scrambling stage.

Key words: image scrambling, scrambling degree, fuzzy set, membership, fuzzy divergence

摘要： 提出了基于模糊散度理论的图像置乱程度评价新方法。首先对置乱前后图像中任意像素所对应二阶邻域系统构造一个模糊集并定义其隶属度；其次计算图像中各像素所对应二阶邻域系统模糊集及其补集之间的模糊散度；最后根据置乱前后两图像的模糊散度来构造图像置乱程度评价函数。实验结果表明，提出的评价方法是能够较好地刻画图像的置乱程度，反映了加密次数与置乱程度之间的关系，与人的视觉基本相符。而且对于不同的图像，该评价方法能在一定程度上反映所用的置乱变换在各置乱阶段的效果。

关键词: 图像置乱, 置乱度, 模糊集, 隶属度, 模糊散度