中文摘要：

该文针对单水印算法往往存在功能单一的问题,利用奇异值的稳定性,提出一种多功能双水印算法。先在图像分块的奇异值上嵌入鲁棒水印,然后在含鲁棒水印图像的空域LSB嵌入脆弱水印,并设计了判别恶意篡改和无意篡改的准则。实验不仅考察鲁棒水印抵抗攻击的鲁棒性,而且还考察脆弱水印对鲁棒性的影响和篡改检测与定位的能力。实验结果表明：鲁棒水印具备很强的抗攻击鲁棒性;脆弱水印对篡改敏感,而且篡改定位精确。因此算法具备版权保护和内容认证双重功能。

英文摘要：

The single watermark algorithms always merely have single function. In order to overcome the drawback, a multi-purpose dual watermark algorithm is proposed in the paper, taking advantage of the stability of singular values. It divides the original image into several blocks, and inserts robust watermark into their singular values. Then it inserts the fragile watermark into LSB in the space domain of previous watermarked image. Moreover, it designs a rule to distinguish malicious tamper from unintentional tamper. It tests not only robust watermark＇s robustness towards attacks, but also fragile watermark＇s influence towards robustness as well as the ability to tamper detection and localization. The experimental results show that the robust watermark possesses strong robustness to resist attacks, and that the fragile watermark is very sensitive to tamper and has good accuracy of tamper localization. Therefore it can achieve copyright protection and content authentication at the same time.