This paper presents an authentication algorithm based on robust watermarking techniques. In particular, the proposed method is based on a self - embedding scheme that is able not only to authenticate noisy images, but also to recover areas modified by a software pirate. The attack method investigated are semantic (altering the meaning of what the image is about) tampering, Gaussian white noise superposition, and JPEG2000 compression. The results are checked against the TAF func- tion, which measure the distance between the inserted and the extracted watermark, and compared to similar algorithms in literature.