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Wavelet domain of digital image watermarking based on spread spectrum mechanism

Author: SunLiJie
Tutor: ZhaoJingXiu
School: Qufu Normal University
Course: Applied Computer Technology
Keywords: Pseudo-random sequence Cycle extension Wavelet Domain Spread Spectrum Watermarking
CLC: TP309.7
Type: Master's thesis
Year: 2011
Downloads: 17
Quote: 0
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Abstract


With the advent of the digital age, the media content in the form gradually from analog to digital transformation, the essential difference between analog content and digital content: First of all analog content and media, digital content and media independent; followed by digital content can be overcome the content shortage copy very simple and does not reduce the quality of the content and content transmission bandwidth; final and the most important is that digital technology has greatly contributed to the emergence and development of new business models. Digital technology allows the multimedia information such as images, text, audio and video, such as a storage, reproduction and dissemination becomes very convenient. However, the problem of copyright piracy and copyright disputes arising become increasingly serious social problems. Existing copyright protection systems use password authentication technologies such as DVD discs secure password. However, merely using cryptographic techniques can not completely solve the problem of copyright protection for data encryption protection the password technology only in the process of data transmission from the sender to the recipient, it does not help the seller surveillance legitimate users how to handle decrypted content cryptographic techniques can only protect the transmission of content, the content is decrypted no longer has a protective effect. In order to solve the lack of cryptographic techniques in data protection, a new effective digital copyright protection and data security to upholding ------ digital watermark technology development. Spread Spectrum as a new means of communication, anti-jamming, anti-noise, low power spectral density, confidentiality, etc.. It uses a pseudo-random sequence for performing spectral spreading of the signal being transmitted, so that the occupier of the channel bandwidth to far exceed the minimum bandwidth in the normal sense of communication necessary. Despreading correlation process on the received signal to synchronize the receiver by using the same pseudo-random sequence and restore data. The spread spectrum technique used in the pseudo-random sequence having the nature of the similar to the white noise, the correlation function has a sharp characteristic, and therefore easy to be separated from the other signals or interference, and has excellent noise immunity. The pseudo-random sequence are typically generated by the binary shift register, and the m-sequence is the most common performance of the pseudo-random sequence. The m-sequence advantage is easy to produce good autocorrelation characteristics, and is the pseudo-random. Short m-sequences the confidentiality of poor and DWT domain shear, translation and compression ability is poor, the first pseudo-random sequences (m-sequences) as the spreading code, the original watermark information cycle extension spread spectrum and encryption determined on the basis of fully consider the characteristics of the human visual spread spectrum watermark in the wavelet transform domain embedding location and strength, spreading sequence selected key sequence determines the maximum number of coefficients of the wavelet transform domain chosen watermark. Theoretical data and experimental results show that the proposed algorithm has strong robustness in geometric distortion attacks and common signal processing and a variety of filtering and other panning certain limitations, but still can be better detected embedded watermark.

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CLC: > Industrial Technology > Automation technology,computer technology > Computing technology,computer technology > General issues > Security and confidentiality > Encryption and decryption
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