安全的变容量恢复水印方案

Safe Variable-Capacity Self-Recovery Watermarking Scheme

针对现有水印算法大多无法准确定位并恢复被篡改区域的问题,兼顾水印嵌入容量和安全性,提出了一种安全的变容量恢复水印算法.该算法首先将原始图像分成纹理块和平滑块,纹理块除了保存常规信息外,还保存了"细节"信息,不同块将根据自身特点产生不同长度的"复合水印".所谓"复合水印"是指水印由认证水印和信息水印构成,其中认证水印用于检测篡改区域,信息水印用于恢复图像.然后采用新提出的"3级秘钥嵌入方案"(three level secret-key embedding scheme,TLSES)将图像块的"复合水印"随机嵌入在其他图像块中,再利用"3级篡改检测方案"(three level tamper detection scheme,TLTDS)定位被篡改图像块并进行恢复.实验结果表明,所提出的水印算法不仅能够准确检测篡改区域并恢复图像,而且能够有效地抵抗均值攻击和拼贴攻击.

Since existing watermarking schemes usually cannot recover the tampered position, a safe variable-capacity self-recovery watermarking scheme is proposed. Both watermark embedding capacity and security are taken into account. The original image is divided into texture blocks and smooth blocks, and the texture blocks not only save traditional information, but also save the ＂details＂ information. The so-called ＂details＂ information refers to the texture information, which not only can effectively resist the mean attack, but also help to improve the quality of the restored image to meet the needs of practical work. And then according to the characteristics of different blocks, the different length compound watermarks are produced. The so-called ＂compound watermarks＂ include the authentication watermarks and information watermarks. Authentication watermarks are used to detect the tampered area, and the information watermarks which include basic watermark and additional watermark are used to restore image. Then the compound watermarks are inserted into the other blocks based on the new proposed scheme called three level secret-key embedding scheme （TLSES）. And then the tamper blocks are detected and restored by the three level tamper detection scheme （TLTDS）. The experimental results show that the scheme can not only accurately detect the tamper region and restore image, but also can effectively resist mean attack and collage attack.