基于数字水印的证件防伪技术

证件防伪是人们广泛关注的社会问题。本文提出了一种基于数字水印的证件防伪技术方案。该方案将水印嵌入到证件持有人的数字照片中,通过对数字照片边界的RADON变换来矫正图像在打印扫描(简称PS)过程中引入的几何失真,以证件号码为种子,产生具有良好自相关特性的随机序列作为水印信号,为提高水印的鲁棒性,采用强度自适应的DCT系数局部调整法,将水印重复多次嵌入到图像的分块DCT中频系数中。水印的提取采用相似度检测法,无需原始的图像。实验结果证明了该方案的可行性和有效性。与其他防伪技术相比,基于数字水印的证件防伪技术具有隐蔽性好,保密性强,技术容易更新,无需特殊材料和工艺,成本较低等突出的优点。

Identification Document Protection Technology Based on Digital Watermarking

This paper presents a new approach for the secure integrity verification of ID cards, passports, diplomas or other identification documents. A invisible watermark is embedded in the owner photo of the identification document holder with the adaptive DCT watermark technology. During verification the owner photo is scanned, the watermark which is extracted through threshold judgement from the scanned photo is compared with the original watermark. The structure of watermark is a random binary sequence with uniform distribution. The ID number is used as a seed to generate the random sequence. RADON transformation of the edge image is used to detect and invert geometric transformations undergone by the scanned image so that the embedded watermark can be successfully determined. Experiment results have demonstrated the feasibility of the proposed approach which has the advantages of high security, high flexibility and low cost.