小波域的扩频数字图像水印算法

该文利用小波变换良好的时频局部特性，提出了基于小波变换的数字图像水印嵌入方案，提高了数字水的隐蔽性，把扩频通信的概念和方法引入数学水印系统，采用了扩频理论中的伪随机序列进行处理，提高了数字水印的稳健性，同时扩频通多址原理也将对实现多重水印起一定的作用。该文详细讨论了该算法的视觉交梨，抗JPEG压缩，抗随机噪声和抗尺寸变换能力，以及多重水印的实现。

IMAGE WATERMARKING TECHNIQUE BASED ON WAVELET TRANSFORM AND SPREAD SPECTRUM

In this paper, the wavelet transform is used to increase the invisibility of the digital image watermark because it can exploit the temporal and spatial phenomena of human visual system. The more robustness can be achieved if watermarks are first spread and then modulated with pseudo noise spread sequence. The multiple address characteristic of spread spectrum will also help multiple watermarking. The performances of the proposed digital image watermarking algorithm based on wavelet transform combined with spread spectrum theory are discussed in this paper, such as resisting the damages from JPEG compression, random noising, geometrical transformation and multiple watermarking.