目的 可逆数字水印技术在遥感、医学、军事等众多领域有着广泛应用，而现有大数可逆水印算法需要依赖于附加信息，严重影响了嵌入容量，为此提出一种无附加信息的大容量可逆水印算法。方法 首先设计了一种类似双线性插值原理的图像放大方法，并利用该方法将载体图像放大为原来的4倍，放大图中有1/4的插值点保留了原始图像信息，其余插值点均可嵌入水印。为了在插值的同时同步嵌入水印，先利用随机函数选取水印嵌入位置，再由嵌入水印信息决定理论插值的最终取值，实现水印嵌入。结果 该方法保证了水印的均匀分布，而且最大限度地降低了嵌入水印对插值的影响，同时还提高了算法效率和水印安全性。与经典插值算法相比，生成的含水印图像质量较好，且对任何载体图像嵌入率均能达到0.75 bit/pixel。结论 大量实验结果表明，算法隐蔽性好、安全性高、嵌入率高、实用性强。

Objective Reversible digital watermarking technology has been widely applied in many fields.Concerning most of the existing reversible watermarking algorithms need a lot of additional information; this paper presents a high capacity reversible watermarking algorithm, which does not need any additional information.This algorithm depends on the image interpolation space.Method First, we design a similar bilinear interpolation image amplification method,and enlarge the cover image by four times its original size. 1/4 pixels of the magnification image retain the original image information,and the other pixels can be embed the watermarking.During the interpolation process.We use a random function to select watermark-embedding position first and then determine the rounding mode and achieve watermark embedding by the watermarking information and the theoretical value.Result This method ensures a uniform distribution of the watermarking and it also minimizes the effect of the interpolation, while improving the security.Compared with the classical interpolation algorithms, the last image is better,and embedding rate can reach around 0.75 bit/pixel.Conclusion Theoretical analysis and experimental results show that the algorithm is reversible and effective and secure.