应用传输分集改善数字水印的稳健性

Application of transmit diversity for improved robust watermarking

许多通常的多媒体信号处理,如剪切、滤波、感知编码等,引起了水印信号衰落状的偏倚。本文提出了一种应用传输分集技术改善数字水印的稳健性的方案。该方案对原始图像作小波金字塔分解,并选择中频子带作为传输信道用来嵌入水印,然后对水印进行伪随机置乱,利用空时编码及其差分检测技术实现水印的嵌入与提取,提取过程无需使用原始图像与估计信道状态信息。实验结果证实了该方案改善了稳健水印的性能。

Many common multimedia signal processing, including cropping, filtering, and perceptual coding, make watermark signal fading-like modification. This paper present a scheme that applies transmit diversity technique to improve robustness of digital watermarking. First, The scheme decomposes the original image using wavelet pyramid algorithm and chooses the middle-frequency band for transmission channel that the watermark will be embedded into. Then the watermark is pseudo-randomly permuted, and makes use of space-time coding and differential detection technique to embed and extract watermark. The extracting process has access to neither the original image nor channel state information. Experimental results demonstrate that the scheme improves the performance of robust watermarking.