A robust watermarking scheme using phase shift keying with the combination of amplitude boost and low amplitude block selection

Watermarking is a potential method for copyright protection and authentication of multimedia data in the internet. The watermarking process can be viewed as a communication task, where the watermark acting like information is embedded into a host image acting like noise in a communication channel which is susceptible to all kinds of attacks acting like jamming. In a previous paper, we proposed a robust watermarking scheme using frequency shift keying (FSK). In the scheme, high-variance block selection (HVBS) is employed to enhance robustness. In this paper, a novel watermarking scheme using phase shift keying (PSK) modulation with amplitude boost (AB) and low amplitude block selection (LABS) is proposed. AB is hired to increase the robustness while LABS is employed to improve the imperceptibility. With proper combination of AB and LABS, the proposed scheme achieves superior performance in terms of robustness and imperceptibility. In order to demonstrate the effectiveness of the proposed scheme, simulations under various conditions were conducted. The empirical results showed that QPSK is the best choice among other PSKs and the proposed scheme can sustain most common attacks including JPEG compression, rotating, resizing, cropping, painting, noising and blurring etc. The empirical results also showed that the scheme with AB and LABS properly combined outperforms the scheme without. The gain of the former over the latter is more significant for host images with smooth characteristics than those with high-frequency characteristics. Simulation comparison with two other schemes (the Hsu's scheme and the Chen's scheme) showed that the proposed scheme is the most robust among the three.