基于DWT的图像水印算法研究

提出了一种基于离散小波变换的水印算法。水印采用文本图像水印，将原始图像和水印分别进行3级小波变换，为了保证水印的安全性，将水印变换域各子图分别进行置乱或加密处理。将水印经处理后的各级变换系数重复嵌入原始图像各级变换系数的不同位置。在检测时，提出采用多方案水印提取算法以适应不同的攻击。实验表明对缩放、剪切、JPEG或JPEG2000压缩等图像退化处理或攻击均具有较强的鲁棒性。

Image watermarking algorithm based on DWT

A new watermarking algorithm for digital images based on discrete wavelet transform (DWT) is proposed. The watermark used here is a text watermark. First, the 3-levelDWT is appliedto the host image and the watermark respectively. To ensure the security, the watermark should be encrypted ordisordered according to each subband. Then the different levels of the watermark frequency domain is repeatedly embedded into corresponding levels of the host image frequency domain in various places. Moreover, multiple extraction methods is presented to cope with various attacks. Experimental results have proved that the method is robust enough to some image degradation process such as resizing, cropping, JPEG or JPEG2000 compression.