Abstract: With the development of digital image enciphering techniques，there appeared a lot of methods including those based on Arnold transformation and affine transformation and those based on theories of Hilbert curve，knight-tour problem，Gray code and etc.However，there are few criteria to measure the merits and demerits of these methods.In this paper some new criteria are provided to formulate the effect of existent enciphering methods.Experiments show that these criteria can also be used to measure the relationship between the enciphering effect and the number of iterations in the enciphering techniques.

Key words: image transformation, correlation, scramble transformation

摘要： 随着图像加密技术的发展，出现了各种各样的加密方法，其中有基于Arnold变换、仿射变换、Hilbert曲线、幻方、骑士巡游、Gray码、混沌序列和基于频域的置乱加密技术，但是却缺少一种能有效衡量这些方法的置乱程度及反映加密次数与置乱程度关系的标准。提出了一种新的基于区域相关的判断置乱程度的方法。实验结果表明该方法能有效衡量置乱程度及反映加密次数与置乱程度的关系。

关键词: 图像变换, 互相关, 置乱变换