基于脆弱水印的可恢复图像认证方案

Restorable image authentication scheme based on fragile watermarking

针对现有脆弱水印算法大多无法恢复被篡改区域的问题,提出了一种基于脆弱水印的可恢复图像认证方案:将分块的DCT系数量化、编码和加密后作为恢复水印,嵌入到偏移子块的次低位;待恢复水印嵌入后,由哈希算法产生分块的认证水印,并嵌入到自身的最低位.理论分析和实验结果表明:该方案在保证篡改定位精度和系统安全性的同时,可有效地恢复被篡改的区域.

Since existing fragile watermarking schemes usually cannot recover the tampered position, a restorable image authentication scheme is proposed. The image is divided into small blocks and each block is DCT（ discrete cosine transform） transformed. A specified number of the lower frequency DCT coefficients are encoded using a fixed number of bits. The resulting bit string as the recovery watermarks are embedded into the second LSB（least significiant bit） of the corresponding excursion block, then the authentication watermarks of each block are embedded into its LSB. Theoretical analysis and simulation 1 results show that the proposed algorithm can not only locate tampered blocks accurately, but also restore the tampered region effectively and ensure the system security.