基于小波变换的数字水印技术

目的研究一种基于二维码的信息化包装防伪技术。方法按照QR编码规则,将文字信息编码生成含彩色底纹的QR码载体图像和QR码水印图像;对彩色二维码进行空间转换提取其亮度分量,对水印QR码图像进行混沌置乱,把置乱后的水印图像利用离散小波变换嵌入到载体图像亮度分量经二级小波变换后的中频系数中,形成嵌入水印后的彩色QR码图像;客户终端运用提取算法从彩色载体QR码图像中提取QR水印。结果实验证明该算法具有较高的水印信息嵌入强度容忍度,并且可以抵抗旋转和剪切等几何攻击,对高斯噪声、椒盐噪声、低通滤波、均值滤波具有较强的鲁棒性。结论将二维码和数字水印结合的防伪技术应用于包装安全领域,有利于识别伪劣假冒商品,达到产品安全保护的目的。

Digital Watermarking Technology Based on Wavelet Transform

The aim of this study was to investigate an informationalized packaging anti-counterfeiting technology based on color QR code. First of all, the original information and watermark were transformed into QR code carrier image containing color shading and QR code watermark image according to the encoding principle, and then space conversion of the color QR code was conducted to extract its luminance component. Chaotic scrambling of the watermark QR image was then conducted, and the scrambled watermark image was embedded into the intermediate frequency coefficient after two-level discrete wavelet transform of carrier image luminance component, forming the watermarked color QR code image. Finally, customer terminal could extract the QR watermark from the color carrier QR code image using extraction algorithm. Experiments showed that this algorithm possessed relatively high watermark information embedding strength tolerance, and it could resist geometric attacks like rotation and cropping. Meanwhile it had relatively high robustness against Gaussian noise, salt and pepper noise, low-pass filtering and average filtering attacks. In conclusion, the application of anti-counterfeiting technology combining two-dimensional code and watermark in packaging safety field could facilitate the identification of fake and shoddy goods and the protection of product safety.