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.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.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.Theoretical analysis and experimental results show that the algorithm is reversible and effective and secure.