Abstract: The new image scrambling degree evaluation method based on fuzzy entropy theory is proposed.This paper firstly constructs the fuzzy set of two-order neighbor system of image pixel and defines its membership function，and then the fuzzy entropy of the fuzzy set that is composed of the pixel belonging to two-order neighbor system is computed，and finally the evaluation function of image scrambling degree is constructed by means of the fuzzy entropy of original 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 entropy

摘要： 提出了基于模糊熵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的模糊熵，最后根据置乱前后两图像的模糊熵构造图像置乱程度评价函数。实验结果表明，提出的评价方法能够较好地刻画图像的置乱程度，充分反映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, 模糊熵