Research On Application Of Hyperchaos Theory In Digital Image Watermarking

With the rapid development of information technology, digital multimedia communications, especially new services such as digital image, digital video, makes information exchange among people more and more convenient. At the same time, the development of information technology brings critical test to digital multimedia communications, that subscribers need urgently to protect individual secrets, so how to identify the copyright, protect the ownership of image, text and video more efficiently becomes more and more important. Under this circumstance, digital watermark, which introduces the privacy scheme on the premise of maintaining the intact data, was developed and had been widely used in many fields. During its transmission, digital watermark needs to resist various attacks and assure the security, so the robustness and security becomes the hotspot of current research.In this paper, we introduce the development and the present situation of digital watermark, analyze its basic principles, especially focus our emphasis on the research of digital image watermark. We propose the digital image watermark algorithm in transform domain based on discrete cosine transform (DCT) and discrete wavelet transform (DWT) separately. The processing of embedding and extraction is described and the watermark scheme adaptive to human vision system (HVS) is presented in detail.To enhance the security and robustness of digital image watermark, the chaotic theory is introduced in this paper. The chaotic system possesses aperiodic and noise-like characteristics, having the natural imperceptibility. The chaotic signal is extremely sensitive to the initial condition, which provides longterm non-predicted and anti-intercept. Meanwhile, chaotic system is deterministic, which makes chaotic signal easy to generate. Making use of these properties, we propose the digital image watermark algorithm based on chaos and DCT. We utilize the chaotic Logistic mapping to encrypt the watermark image, embed the encrypted watermark image into the non-zero DCT coefficients of the image by adopting the adaptive watermark embedment strength to advance the invisibility. Simulation results show that the proposed algorithm improves the invisibility and anti-attack.The digital image watermark based on chaos and DWT is proposed in this paper. We embed the watermark image encrypted by chaos into the vertical DWT component of the host image. According to the energy, we determine the embedment strength to reflect the HVS. Simulation results show that the proposed algorithm improves the robustness.Compared with the chaos, hyperchaos is more suitable for encrypting the digital image watermark. Hyperchaos has more complex track, which makes hyperchaos more random, difficult to decipher. Owing to its security, hyperchaos provides a novel scheme of encrypting the digital watermark.The paper introduces the hyperchaotic theory, discuss the feasibility of using hyperchaotic system to encrypt the 1-dimension data and reveal the application potential of hyperchaos in information encryption. We expand the hyperchaos to the encryption of 2-dimension image. Combining the DCT and DWT, we embed the watermark image encrypted by hyperchaos into the insensitive location of the original image according to the HVS. Simulation results show that the proposed algorithm is invisible and robust to resist the Gaussian noise and JPEG compression.