图像的自嵌入及窜改的检测和恢复算法

提出一种图像自嵌入的水印算法.它将一个图像的主要内容嵌入该图像自身之中.该算法不仅能检测和定位对图像的窜改,而且能恢复被损坏的图像内容.算法的基本思路是把一个图像块的主要DCT系数经过量化、编码和加密后,嵌入另一个图像块的最低位之中.依据大量图像DCT量化系数的统计性质,本文仔细设计了主要DCT系数的编码表,使它既能满足水印负荷的要求,又能保证图像恢复时有较好的质量.分析了水印嵌入块和原图像块间偏移值应该满足的条件和设计方法.该算法为单向、不可逆的,可以抵抗可能的伪造攻击.

Tamper Detection and Self Recovery of Images Using Self-Embedding

A scheme for self-embedding an image into itself is proposed as a means for detecting and locating tamper,and self-recovering.The image is divided into small 8×8 blocks and each block is DCT transformed.A specified number of the lower frequency DCT coefficients are quantized and encoded using a fixed number of bits.The number of coefficients and their bit lengths are carefully chosen,according to the statistical property of these coefficients,the resulting bit-string for each block satisfies the payload of each block and has good self-recovering capability.The information about one block B (the bit string) is inserted into the LSB of another distant block,which is separated from B with an offset.We analyzed the method for choosing the offset.The proposed scheme is an one way watermarking and secure algorithm,and can well resist possible forged attack.