目的 为了抵御 QR 码数字水印图像的几何攻击，提出一种基于奇异值分解和离散小波变换的数字水印技术。 方法 利用 QR 码编码规则，将文本信息编码生成宿主图像；将宿主图像进行对数极坐标变换，然后进行一级小波分解，利用奇异值分解原理在其低频分块中嵌入置乱后的水印图像，形成含水印的 QR 码图像。 结果 实验结果表明，该算法可以使 QR 码水印图像抵抗旋转、缩放、平移（RST）等几何攻击。 结论 算法有良好的鲁棒性和不可见性，能够作为一个可行的版权保护和认证的工具。

In order to enhance the resistance of QR code watermark image against geometric attack, the paper proposed a new watermarking algorithm based on singular value decomposition and discrete wavelet transform. The text information was transformed to host image by the principle of encoding; then the logarithmic coordinates transform was applied to the host image. Afterwards, the scrambled watermark was embedded into the low-frequency sub-block of the host image through discrete wavelet transform using singular value decomposition principle, forming the watermarked QR code. Experiments showed that this algorithm could make the QR codes watermark image resist rotation, scaling and translation (RST), and other geometric distortions. The algorithm had good robustness and invisibility, and can thus serve as a viable copyright protection and authentication tool.