摘要： 基于数字水印的快速响应矩阵(QR)二维条码防伪技术的水印容量低、防伪效果差。为解决该问题，提出QR码二值图像Rand灰度化和背景图灰度化方法，以提高防伪水印容量。QR码二值图像灰度化的程度由灰度化阈值决定，并且可以根据实际应用需要灵活确定。在此基础上，设计基于离散小波变换的QR二维条码防伪水印方案，通过量化函数实现水印的嵌入和检测，利用混沌密钥生成的二维混沌序列控制水印嵌入和检测的位置。实验结果表明，该方案在确保条码信息可识别的条件下，提高了QR码防伪水印的性能。
关键词:
数字水印,
防伪,
快速响应矩阵码,
二值图像,
离散小波变换,
二维条码
Abstract: The Quick Response(QR) barcode anti-counterfeiting technique based on digital watermarking provides low watermarking capacity, and its anti-counterfeiting performance is poor. To solve the problem, Rand-graying method and background-image-graying method are proposed for QR binary images to increase watermarking capacity. The graying extent for QR binary image is determined by the graying threshold which can be selected according to specific application. Based on the graying methods, the anti-counterfeiting QR 2D barcode watermarking scheme based on Discrete Wavelet Transform(DWT) is designed. In the proposed scheme, watermarks embedding as well as watermarking detection are made by a quantization function. In addition, the positions for watermarking are determined by 2D chaos sequence generated from well designed chaos keys. Experimental result shows that the proposed watermarking scheme for QR 2D barcode improves anti-counterfeiting performance without loss of any bar code information.
Key words:
digital watermarking,
anti-counterfeiting,
Quick Response(QR) code,
binary image,
Discrete Wavelet Transform(DWT),
2D barcode
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