Combination Of Dual Space-frequency Domain Based On The Sub-block Watermark

With the development of networks and technologies of communication, a information era arrives and digital products are becoming more and more related to our life, thus making it more important to protect intellectual rights of digital products. As a technology of protection and hotspot of time, digital watermarking hides invisible information like identification and copyright in the will-protected digital products and presents them when needed. This issue mainly focuses on double watermarking technology in terms of the following respects:1.This issue presents a technology of double-level watermarking which can simultaneously imbed watermarking information in blocks in space domain and integrate multi-scale wavelet transform and HVS in frequency domain. In this technology, the algorithm of space domain owns abilities to defend geometry attacks such as rotation, scaling and translation. Meanwhile, the algorithm of frequency domain has characteristics of resisting compression, noise, and filtering by adopting multi-scale wavelet transform technology.2. Integrating HVS technology which is related to human visual system and algorithm of watermarking, the digital watermarking embeds watermarking information into different color channels and fields of image, thus being transparent and robust.3. Making use of strong anti-interference of SVD, the issue suggests an improved algorithm of watermarking which is based on a combination of blocked LSB algorithm in space field and DWT_SVD in frequency field. Experiments show that this algorithm can strongly resist attacks from outside.4. In order to reduce complexity and increase efficiency of calculation, this issue adopted the blocking technology. Experiment results show that the utilization of blocking technology strengthened the embedment of watermarking in space field and makes the algorithm more resistant to compression as it is very similar to popular data compression techniques.Experiment results prove that the algorithm presented in this issue can resist common geometry attacks, compression attacks, noise attacks and filtering attacks etc, and has a very good invisibility, thus making it effective and practical.