两个新的数字图像加密效果评价准则

Two New Digital Image Encryption Effect Evaluation Criterions

图像信息熵和灰度变化平均值是两个常用的图像加密效果评价准则。分析指出,图像信息熵和灰度变化平均值受图像尺寸大小的影响较大,为此提出了两个新的图像加密效果评价准则:直方图均衡度和游程统计量。直方图均衡度可用于基于像素灰度值变换的加密过程的评价,游程统计量可用于图像坐标置换的加密过程的评价。新方法表达简单,计算便捷,其显著优点是与图像大小无关,不需要借助原图像。

Image information entropy and gray modification average value are two familiar image encryption effect eva- luation criterions. We pointed out that these two criterions are influenced obviously by the size of images,and two new image encryption effect evaluation criterions were presented, that is,histogram proportion degree and run statistic. His- togram proportion degree can be used in the effect evaluation of image encryption algorithm based on the image pixel gray values modification, and run statistic can be used in the effect evaluating of image encryption algorithm based on the image pixel coordinate permutation. The proposed criterions are simple on expression and convenient in computation, their main advantages are having litter effect on the size of images and the computing process are only related with the encrypted image.