Image Watermarking Robustness Of The Algorithm

As an efficient approach to protect the copyright of digital multimedia, digital watermarking technology is becoming a hot research point in both inside and outside. Imperceptibility and robustness are two important features at which robust watermarking must to reach, however, the two features are incompatible. So how to get good balance between the two features is the main problem to design a watermarking algorithm. How to improve the watermarking's robustness on the premise that the watermarking is imperceptible is deeply researched in this paper. The principle work and achievements of this paper are shown as follows:1. Researches of classical watermarking schemes. Through simulation results of space-domain typical watermarking scheme-LSB and frequency-domain typical watermarking scheme-NEC, advantages and bugs of algorithms in the two domains are shown. The watermarking frameworks are also provided by analyzing typical algorithms.2. A blind watermarking algorithm for color images is designed. Host image in RGB space is converted to YIQ space and DWT and block-DFT were applied on it. Combining a template matrix and two pseudo random sequences, the binary watermarking image which has been scrambled by implementing Arnold transform is embedded into the host image. Original watermarking image and host images are not necessary when detecting. Experimental results show the proposed algorithm has good performance in both invisibility and robustness against common image processing.3. A watermarking algorithm which is both robust to geometric distortion and common image processing is designed. Watermarking messages combined a Gaussian-noise template are embedded to vertical high frequency coefficients which are produced by one-level integer wavelet transform of the host image. Then the same messages are embedded to each sub-image by quantization repeatedly. Two watermarking images are extracted by correlation calculation and majority rule. Finally, the ultimate watermarking is decided by a judge rule. Experiment results show the algorithm is both robust to geometric attacks and common image processing, meanwhile, the imperceptibility of the algorithm can meet the request.