一种基于DCT域的数字图像置乱程度衡量方法

图像的置乱变换在图像加密和信息隐藏中有广泛地应用。对置乱程度进行衡量,能够指导我们设计具有更高置乱程度的置乱算法。在考虑置乱图像的纹理细节特征的基础上,利用DCT变换的能量集中特性,提出了一种基于DCT域的图像置乱程度定义。由Matlab实验结果表明,所给的定义能较好地描述图像的置乱程度。它既能较好地衡量同一种置乱算法置乱次数与置乱效果的关系,也能较好地比较不同置乱算法之间的置乱效果,而且和人的主观评价基本一致。

Image scrambling degree evaluation method based on DCT transformation

Image scrambling transformation is a common method in image encryption and information hiding. It is of major importance to evaluate the image scrambling degree （ISD）. It is helpful to decide what kind of transformation to be selected to scramble an image, in order to obtain the best effect. A new method for objectively assessing the ISD is presented. The method utilizes the performance of energy concentration of DCT transformation and takes into account the texture characteristics of an image. Experimental results of Matlab show that the proposed method is effective to assess the ISD , which correlates well with subjective assessment. It can measure not only the relationship between the times of image scrambling and the ISD of one scrambling method, but also the differences of scrambling effects among different scrambling methods, which is accordant with human sub- jective judgement.