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。(An adaptive watermark blind watermarking algorithm based on QR codes is proposed. Methods first of all, the carrier QR code is three levels smaller.
Wave transformation and 4 *4 block Schur decomposition of the low frequency part are carried out. Then the binary values are obtained by using the stability of the coefficient difference of the subblock unitary matrix.
The watermark information is embedded into the carrier QR code adaptively. Finally, the watermark information is extracted by scanning the watermark QR code. At the same time, the algorithm achieves blind extraction. Results The algorithm can resist the attack of print and scan, and can resist Gaussian noise, salt and pepper noise, speckle noise, Poisson noise.
JPEG attacks such as compression have strong robustness. Conclusion the algorithm has strong resistance to print scanning and can be widely used in digital products.
Copyright protection.)