基于混沌加密的QR码彩色图像复合水印算法

Compound Watermarking Algorithm of the Color Image Based on Chaotic Encryption and QR Code

本研究提出了一种基于NSCT-DWT-SVD复合的QR码混沌加密彩色图像水印算法。首先将“飞行学院”四字组成的水印图像通过编码器进行QR编码生成QR码水印信息,再对水印进行Logistic混沌映射加密,将RGB颜色模型的原载体图像转换成YUV颜色模型图像,对转换后的模型Y分量进行提取,将其进行NSCT生成低频分量,随后进行小波变换及SVD奇异值分解获得奇异值,最后将加密的QR码通过加性原理叠加到分解后的奇异值上。通过实验证明,该算法得到的峰值PSNR为52.15dB,保证了嵌入水印的信息量及隐蔽性,对椒盐噪音、JPEG压缩攻击NC值都为1,尤其是由于加入NSCT保证了图像的平移不变性,SVD更是提高了算法抵抗旋转攻击的能力。

In this study,a color image watermarking algorithm based on NSCT-DWT-SVD composite QR code chaotic encryption was proposed.Firstly,the watermark image composed of the four characters“Flight Academy”was QR coded by the encoder to generate the QR code watermark information.The watermark was encrypted with Logistic chaotic map.The original carrier image in RGB color space was converted into YUV color space.The component Y of the converted model was extracted.The component Y was performed the NSCT to generate the low frequency components.Then,the wavelet transform and SVD singular value decomposition were performed to obtain singular values.Finally,the encrypted QR code was superimposed on the decomposed singular value through the additive principle.The experiments showed that the peak PSNR obtained by the algorithm is 52.15dB,which guarantees the amount of information and concealment of the embedded watermark.The salt,pepper noise and the JPEG compression attack have an NC value of 1.Especially since the addition of NSCT ensures the translation invariance of the image,SVD improves the algorithm’s ability to resist rotation attacks.