数字水印技术英文文献

Discussion on the digital watermarking technology in electronic reading business applications
Abstract: the business era, the market competition is fierce day by day. Have broad prospects of electronic reading business may become the carrier of new profit growth point. Digital watermark technology in electronic reading content copyright protection of some of the application, make a preliminary study and discussion, and puts forward some suggestions
Key words: digital watermarking; copyright protection of electronic reading;
Preface
Since China telecom carrier recombination and 3G licences, the domestic telecommunication market competition is intense with each passing day. Facing market competition pressure, how to play their own advantages to gain competitive advantage, has become the major operators must solve the problem.
In the telephone business is gradually replacing mobile communication, broadband market is nearing saturation, the traditional mobile voice revenue ARPU values in the great pressure of competition is also very difficult to have the breakthrough of the severe form, as an emerging business electronic reading become carriers of potential revenue growth.
Electronic reading, is defined in PC, laptop, mobile phone and other portable electronic terminal reading novels, newspapers, magazines and pictures and other traditionally printed on paper carrier content reading. Compared with traditional way of reading, reading in the acquisition mode, distribution channels, sales management, payment means and environmental protection has natural advantage. With the 3G network of perfection and the mobile phone terminal screen, intelligent development trend, relying on more than 700000000 of mobile phone users, electronic reading have a broad market prospect.
Electronic reading business core content is the use of the traditional means of communication to provide rich multimedia resources. At present, China's copyright protection situation is not optimistic, the literature works of infringement acts have occurred. Electronic reading success, largely dependent on the copyright management. Therefore, for copyright protection and digital watermarking technology in electronic reading business will play a very positive role.
1 digital watermark
1.1 What is the digital watermarking technology
Digital watermark technology is through a certain algorithm will landmark information directly embedded into the multimedia content, but not affect the original content value and use, and can not be aware of the perceptual system or pay attention to, only through a special detector or reader to extract. Digital watermarking technique can distinguish whether the object is under protection, monitoring of the protected data transmission, authentication and illegal copy, resolve copyright disputes, and to provide evidence to the court.
Copyright protection digital watermarking to requirements
1) validity: in copyright protection digital watermarking embedded content should
have authority, that is to say should be able to show that the carrier file ownership is recognized; 2): a robust watermarking anti-attack ability; 3) capacity: refers to embed information in the file number; 4) imperceptibility: refers to the embedded watermark information file with the original documents should be almost the same or does not influence the normal use of the files, but also users can not feel the existence of watermark.
2 Digital watermarking technology in application of electronic reading
Digital watermarking of a series of technical characteristics show that, in the rapid development of the electronic reading service, digital watermarking will be widely used.
For image, video watermarking algorithm
Discrete cosine transform digital watermarking is often used as a basic transformation. First introduced the definition of discrete cosine transform:
On digital image,
The two dimensional DCT transform is defined as:
Two dimensional inverse DCT transform ( IDCT ) is defined as:
By 3.2 the original image can be expressed as, for a series of weights
When a pair of pixels in an image matrix after discrete cosine transform, the frequency domain matrix in left corner element value maximum, for the DC component, representing the whole image of the average brightness; while the remainder of each element value according to the corner element for fixed-point
triangle lateral snaking arranged successively, representing the image low frequency, medium frequency components and high frequency components.
Cox presents a global DCT domain watermarking algorithm:
Selection of sequences of X = x1, x2, ... , xn as watermark, where Xi is satisfy the Gauss distribution of N (0, 1) of a random number. The algorithm first uses the discrete cosine transform of the original image I is transformed into the frequency domain, using the D representation of the data obtained. From the coefficient of D select n most important frequency component, consisting of sequences of V = V1,
v2, ... , VN, in order to improve the robustness of image compression.
Get the watermark array and frequency domain array, using the formula: Vi=vi ( 1+α XI ) digital watermark is embedded into the frequency domain array carrying watermark information, get new frequency domain array sequence of V = V1, v2, ... , VN, then the V' of each element in the frequency domain matrix D in the corresponding position of the V element replacement out, get a new frequency domain matrix D, the D inverse discrete cosine transform be containing the watermark watermark image I. In the watermark image I* for watermark detection, the whole process is the reverse process of embedding process almost. The first is to I* through DCT to obtain the frequency domain array sequence of V* = v1*, v2*, ... , vn*, then according to the formula Vi=vi ( 1+α XI ) inverse formula one watermark sequence of X* = x1*, x2*, ... , xn*, then calculate the watermark with the original watermark correlation of X* X.
The algorithm is robust, can resist including scaling, JPEG compression, shear and jitter, printing and copy - scanning, image processing, and then embedding
Multi-watermarking, also can resist attacks multiple users, is a very effective watermarking algorithm.
2.2 text digital watermarking
With the picture or video files, text files without too much redundant information space, so the text based watermarking technique is far less than the image or video. Commonly used text watermarking is based mainly on the fixed format text watermarking. Commonly used methods: Based on the spacing of information representation, based on the word spacing information representation method and based on the character attribute information representation. In actual use, can these three kinds of information hiding methods combination.
Based on the fixed format text watermarking, its biggest weakness is to retain the text but change the text format of soft copy sensitive. In order to solve this problem, people put forward based on the text semantic watermarking technology, but this
technique is difficult to realize and watermark extraction need to provide source file control, maneuverability is not strong.
In the actual electronic reading, we will be able to distribute content using the format developers to provide tools for content set can not be copied ( word, PDF have this feature ), to avoid illegal user to destroy the watermark information. In addition, also can be a text scanning for picture format, using the discrete cosine transform technology to embed the watermark, and then provided to the user.
3 Summary
In an electronic reading business applications, digital watermarking technology mainly focuses on the identification of the infringement, also cannot prevent and stop the infringement occurred. And the robustness of digital watermarking algorithm can not completely meet the needs of. But with the continuous progress of watermarking algorithm, and with the use of CA technology and the encryption technology, digital watermarking technology in electronic reading areas will have more extensive application.。