基于极性调制的鲁棒水印算法

Robust watermarking algorithm based on polarity modulation

为满足地理信息版权保护对裁剪、拼接等攻击的强鲁棒性要求,通过构造二值序列分别表示水印0和1,利用变换域系数极性相对稳定的特点,通过调制极性序列与二值序列的相关系数嵌入水印,提出了一种基于变换域系数极性的水印算法。基于变换域系数特殊分类的极性序列分布在整个DCT域,增强了算法抗裁剪的能力;而且水印提取策略能够抵抗图像拼接攻击。实验结果表明,该算法具有良好的不可见性,可抵抗亮度(-90^+90)、对比度(-90^+80)、放大、裁剪、拼接的单独攻击,对综合攻击也有较强的鲁棒性。

To withstand various attacks such as cropping and image mosaic in geography information copyright protection, a transform coefficient polarity based watermarking algorithm was proposed. In this algorithm binary were constructed to represent watermark bit 0 and 1 respectively. Since polarity is almost invariant, watermarking can be embedded by modulating the correlation value between polarity sequence and binary sequence. Special classification based polarity sequence distributing in whole DCT domain may increase robustness against cropping. Moreover, watermark retrieval scheme is resilient to image mosaic. Experiments show that the proposed method has good watermark imperceptibility, and resistant to light variety from -90 to 90, contrast variety from -90 to 80, scale, cropping and image mosaic, and it is robust for combined attack.