基于QR码的DWT-DCT数字水印算法

数字水印在版权保护中广泛运用。为了提升版权信息的完整性和有效性，水印需要具备高强度的隐蔽性和抗攻击性。因此文中提出了一种结合快速响应码（QR）、混沌系统和DWT-DCT的鲁棒性水印方案。首先通过混沌系统产生的混沌序列对QR进行加密；然后将宿主图片进行DWT操作，并且对低高频子带进行4×4分割和DCT操作；最后利用水印信息产生2×2矩阵，叠加到DCT变换后矩阵的右上角。在水印信息提取时，通过对比叠加矩阵中的元素并统计元素变化率，以此确认提取的水印信息。模拟实验分析表明，该方案不仅能够增强水印信息的透明性，而且在涂画、切割、噪声、过滤和Jpeg压缩等攻击中具备较强的抗攻击能力。

A algorithm of DWT-DCT digital watermarking based on QR code

Watermarking is widely used in copyright protection. In order to improve integrity and effectiveness of the copyrights, watermarking is required to have high strength concealment and robustness. So a new robust watermarking scheme was proposed in this paper, and it combined Quick Response Code (QR), chaotic system and DWT-DCT. Firstly, the chaotic system generating chaotic sequences used to encrypt QR. Secondly, processing the host image by DWT, then the low frequency sub-band was divided into blocks which its size 4*4, and performing DCT on the blocks. Finally, the watermark information is used to produce a 2 * 2 matrix, and adding it to the upper right corner of the DCT transform matrix. When the watermark information extracted, comparing the elements in the superposition matrix and the change rate of the elements to confirm the watermark information. The simulation results show that the scheme not only can enhance the transparency of the watermark information, but also can have strong robustness in cutting, graffiti, noise, filter and Jpeg compression attacks.