中文摘要：

为了实现对多媒体数据版权的有效保护,采用小波变换和图像子采样技术,提出一种彩色图像水印新算法。水印嵌入时,先对宿主图像在YIQ色彩空间中的Y分量进行子采样,并对得到的4个子图像分别进行二级离散小波变换,然后,将经Arnold变换置乱后的水印图像嵌入到小波变换后的低频子带中,其嵌入位置由TD-ERCS混沌系统产生的混沌序列确定。采用盲提取算法进行水印提取。研究结果表明：嵌入水印后的图像质量高,水印隐蔽性好;水印图像能抵抗JPEG压缩、噪声、滤波、图像锐化、直方图均衡化、剪切和旋转等攻击,鲁棒性好;用于水印提取的密钥空间大,增强了水印的安全性。

英文摘要：

In order to protect copyrights of multi-media data effectively,a novel color-image watermarking algorithm was proposed based on wavelet transform and subsampling.The watermark was scrambled by 2-D Arnold cat map,and the scrambled watermark was embedded into the low sub-bands when four sub-images of the Y branch of host image were transformed by two-level wavelet transform,and the embedded positions were determined by TD-ERCS chaotic map.Blind extraction was used to realize this watermarking scheme.The results show that the proposed algorithm keeps the quality of the image well and is robust enough for JPEG compression,noise,filtering,image enhancement,histogram equalization,cropping and rotation etc.Security keys are required to extract the watermark,and the space of security keys is large,which ensures the safety of the watermark.