为了提高图像的安全性，增强图像的加密效果，提出一种基于离散小波和分数阶傅里叶变换（FRFT）的图像加密算法。首先利用离散小波变换使图像信号稀疏化，然后对稀疏化处理后的图像进行离散FRFT处理，得到最终加密图像。MATLAB的仿真结果表明，和单一的小波变换相比，该算法的加密和解密效果较好，能够较好地隐藏图片的信息。

In order to improve the security of the image, and to enhance the effect of encryption, an image encryption algorithm based on discrete wavelet and fractional Fourier transform（FRFT）is proposed. Firstly, the discrete wavelet transform is used to make the image signal sparse, then the discrete fractional Fourier transform is used to deal with the image of sparse processing, and the final image is obtained. The MATLAB simulation results show that compared with the single wavelet transform, the algorithm has better encryption and decryption effect, and can hide the information of the image better.