中文摘要：

提出一种基于分数傅里叶变换和小波分解的彩色图像分级加密方案。通过对图像矩阵和颜色索引表分别进行加密来实现彩色图像的分级加密。先对颜色索引表进行Logistic置乱,得到一级加密图像;再对图像矩阵进行单层小波分解提取出低频分量,对其进行分数傅立叶变换域的双随机相位编码,得到二级加密图像,将置乱的颜色索引表和加密之后的图像矩阵合成生成加密图像。该方案具有较高的安全性和效率,仿真结果验证了算法的安全性和有效性。

英文摘要：

A color image hierarchical encryption scheme based on fractional Fourier transform and wavelet decomposition is presented.The color image hierarchical encryption is realized by encrypting image data matrix and color index table respectively.The color index table is scrambled by using Logistic algorithm at first to obtain the first-level encrypted image.Afterwards,the image data matrix is dealt with single level wavelet decomposition and then the low-frequency component is encoded by double random phase encoding in fractional Fourier transform domain to obtain the second-level encrypted image.The final encrypted image is obtained by combining the scrambled color index table and the encrypted image data matrix.The scheme features high security and efficiency and simulation results verify the security and the validity of the proposed encryption algorithm.