3 / 2016-09-17 11:55:30

Dual Channel Watermarking – A Filter Perspective

11301,11300,7444,11302

Spread spectrum (SS) is one of the most commonly used watermarking techniques, but it suffers from host signal interference during watermark extraction. Besides the well known developments of classical host interference rejecting SS techniques, i.e., improved spread spectrum (ISS) and correlation aware improved spread spectrum (CAISS), a simple and effective treatment could be splitting the host signal into two channels (even-sample channel and odd-sample channel) before watermark
embedding. Host signal interference is then suppressed by reconstructing the channels and taking the difference of them. This paper analyzes such a dual channel scheme from the perspective of digital filtering. We show that the dual channel
based watermark extraction actually applies a high pass filter to the watermarked signal, and the performance when the filter coefficients are changed is also studied. The effectiveness of the dual channel scheme in rejecting host signal interference
is confirmed via extensive experiments using both synthetic and real audio and image signals.