说明：  其使用dct的方法实现图像水印，经检测，其鲁棒性较好，原图像不可见性也较好。包含了加密解密算法，可以实现不需要原图的解密。
(The use of dct method to achieve image watermarking, after testing, its robustness is better, the original image invisibility is better. Contains the encryption and decryption algorithms, you can achieve the original image does not require the decryption.)