目的 提出一种基于QR码的自适应抗打印扫描盲水印算法。方法 首先对载体QR码进行三级小波变换，并对低频部分进行4×4分块Schur分解，然后利用子块酉矩阵的系数差值的稳定性，将二值水印信息自适应嵌入到载体QR码中，最后对含水印QR码打印扫描并提取出水印信息。同时，算法实现了盲提取。结果 算法能较好抵抗打印扫描攻击，并对高斯噪声、椒盐噪声、斑纹噪声、泊松噪声、JPEG压缩等攻击具有较强的鲁棒性。结论 算法具有较强的抗打印扫描性能，可以广泛应用于数字产品的版权保护。

The work aims to propose an adaptive blind watermarking algorithm resistant to printing and scanning based on QR code. Firstly, the carrier QR code was processed by three-level DWT transform and the low-frequency part was subject to 4×4 block Schur decomposition. Then, the binary watermarking information was adaptively embedded into the carrier QR code based on a stable coefficient difference of sub-block U matrix. Finally, the watermarking information was extracted from the QR code which was printed and scanned. Meanwhile, the algorithm was blindly extracted. The experimental results showed that the algorithm could better resist print-scan attack, and it had higher robustness in resisting the attacks like Gaussian noise, salt and pepper noise, speckle noise, Poisson noise and JPEG compression. With strong performance in resisting prin-scan attack, the algorithm can be widely applied in the copyright protection of digital products.