基于量化的扩频水印技术

随着计算机和网络技术的飞速发展，数字图像、音频和视频产品越来越需要一种有效的版权保护方法，数字水印技术为上述问题提供了一个潜在的解决方案。提出了一种基子量化的扩频水印技术，算法将水印信号与序列作扩频调制，调制信号通过量化策略嵌入到块ＤＣＴ变换系数的低频分量中，在嵌入过程中考虑到了局部图像的复杂度，能够自适应地调整嵌入强度，提取水印信号无需使用原始图像。仿真实验表明水印是不可察觉的，经过 ＪＰＥＧ有损压缩、低通与中值滤波、剪切等图像处理操作后仍是稳健的。

Spread Spectrum Watermarking Technique Based on Quantization

The advent of Internet and the wide availability of computers, scanners and printers make digital data acquisition, exchange and transmission a simple task. Digital watermarking techniques have been proposed as a solution to the problem of copyright protection of multimedia document. This paper presents a spread spectrum watermarking technique based on quantization. It uses m - sequence to modulate watermark. The modulated signal is embedded in the low frequency band of block - DCT by quantization. The scheme can adaptive adjust embedding strength according to local image complexity and can extract the watermark without the original image. Experimental results show that the proposed scheme is robust to some image processing operations such as iossy JPEG compression, low pass filtering, median filtering, cropping.