DWT-DCT联合变换域上的文本图像水印方案

Text image watermarking scheme using DWT-DCT joint transform

为解决单一水印加密算法安全性差,单一变换域的水印嵌入、提取算法在抵抗攻击上各有侧重,难以抵抗所有常见攻击类型的问题,提出基于DWT-DCT联合变换与二次加密技术的文本图像水印算法。利用DWT、DCT对滤波、JPEG压缩等攻击的抵抗优势和特性,将经过二次加密的水印进行差错控制编码,嵌入到DWT-DCT联合变换域的中频区域,加强安全性,抵抗常见攻击,特别是剪切攻击和噪声攻击。实验结果表明,该算法可有效保证水印算法的不可见性,提高水印抵抗JPEG压缩、噪声、滤波、剪切等攻击的鲁棒性和安全性。

The unitary watermark encryption algorithm showa poor security,and watermark embedding and extraction algorithms based on a unitary transform domain has different emphases on resisting attacks,and it is difficult to resist all common attack types.To address the problems,a text image watermarking algorithm using joint transform based on DWT-DCT and secondary encryption technology was proposed.The double encrypted watermark was encoded by error control,and was embedded into the intermediate frequency region of the original text image after DWT-DCT joint transformation.On this basis,the extracted feature sequence was used to complete the secondary encryption to obtain the encrypted watermark.Experimental results show that the proposed algorithm can effectively improve the security of watermark and the robustness to compression,noise and filtering,clipping and other attacks on the premise of ensuring the invisibility of watermark with advantage.