一种用于图像篡改定位的半脆弱数字水印算法

Semi-fragile digital watermarking algorithm for image tamper localization

设计并实现了一种用于数字图像内容认证的半脆弱水印方案。算法中,图像块的水印选择Logistic映射作为混沌系统从该图像块本身产生一系列混沌序列,作用于水印的嵌入;每个图像块产生的水印按照Torus,自同构映射嵌入另一个映射块的LSB(Least Significant Bit),对应关系通过密钥来确定,这样建立起图像块之间的相关性;利用混沌对初值极端敏感性的特点,能够定位检测对加入水印图像的篡改,且水印提取不需要原始图像。实验结果表明,嵌入水印后的图像的视觉好;算法具有图像内容局部篡改检测的有效性、敏感性以及良好的篡改定位能力。

A new semi - fragile watermarking algorithm for image content authentication based on chaotic mapping is presented. Chaotic sequence generated from the block itself by means of Logistic mapping is used to generate watermarking embedding; then the generated watermarking information is embedded into LSB plane of another image block with Toms Automorphisra mapping, which the corresponding relation is determined by the secret key to establish the correlation among the image blocks. The results show that the method could localize the tampered watermarked image by using the high sensitivity on initial value of the chaotic mapping without host image in watermark extraction. Moreover, watermarked images obtained have good subjective quality, precise localization of tampered areas, and the algorithm is simple and safe.