Research Of Watermarking Based On Spread Spectrum Techniques

Digital watermarking is a technique for embedding a secret signal (watermark) into a host media in an imperceptible fashion, aiming to protect the copyright and content authentication. Digital watermarking has a high demanding prospect on copyright protection, integrity verification, data tracing, commercial VOD.Spread spectrum was originally developed for military applications. It has the advantage of efficiency in frequency reuse, anti-interference, high security, etc. After the use of spread spectrum techniques in digital watermarking, spread spectrum watermark generation techniques have played an important role in digital watermarking. In this paper, thorough researches on watermark techniques are presented based on the spread spectrum techniques. Four basic spread spectrum watermark generation techniques have been proposed in this paper, witch contain the watermark technique based on chip rate, the watermark technique based on period extension of pseudo random sequence, the watermark technique based on soft spread spectrum and the watermark technique based on CDMA. Four new watermarking algorithms have been proposed based on the above techniques. The main contributions of this paper are listed as follows:1. A novel watermarking algorithm base on synchronous gradual enhancement theory has been proposed. The binary watermark image was transformed by lift integral wavelet transform (LIWT). The approximate coefficients and detail coefficients of watermark were embedded by different embedding intensity. The load image was decomposed and transformed watermark sequence was amplified synchronously for the multi-resolution decomposition property of wavelet theory. The blind extraction could be realized by utilizing single polar quantification method.2. A new effective adaptive watermarking algorithm based on the features of image local texture. A pseudo random sequence was produced after comparing these variances with the variance of the whole load image. The blind extraction could be realized by utilizing the odd-even adjudgement rule. Experimental results show that the watermark proposed in this paper is invisible and is robust against some normal attacks such as JPEG compression, additive noise and filtering etc..3. A novel watermarking algorithm based on FH/DS system has been proposed. Direct sequence spread spectrum techniques and frequency hopping spread spectrum techniques have both applied in this scheme effectively. Duo keys were applied in this algorithm so that the confidentiality and anti-interference property have enhanced greatly. Blind extraction has been realized in this algorithm.4. A novel adaptive bind watermarking algorithm based on CDMA has been proposed. The watermark sequences have been spread spectrum by generating balancing Gold codes. The spread spectrum watermark sequence has been embedded in the middle and high frequency wavelet coefficients of the load image. The double mode means of neighborhood quantification algorithm has been introduced as quantification method. The advantage of this algorithm are extraction easily and high adaptability...