The most popular digital product anti-counterfeiti

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With the development of digital technology and Internet, various forms of multimedia works (images, video, audio, etc.) have been published in the form of networks. However, the convenience and insecurity of digital works also coexist. It can be copied and transmitted at low cost and high speed, which provides great convenience for creators and users, However, these characteristics are also easy to be used by pirates, so using a variety of means to protect digital products and punish infringers has become an urgent work. In addition to the legal and management means similar to the traditional copyright protection of works, we should also provide technical protection for digital products according to their own characteristics. The research of digital watermarking technology has developed rapidly under this demand. Digital watermarking technology is different from traditional watermarking paper. It uses the related technology of digital signal processing to embed trace data (generally digital, serial number, text, image logo and other copyright information) in media works. After the watermark technology is embedded, the original media data has not changed, nor does it affect the normal use of the original data. The digital watermark makes people unable to perceive the watermark from the surface. Only a special detector or software can detect the hidden watermark. At the same time, through the detection and analysis of watermark to ensure the integrity and reliability of digital information, it has become an effective means of intellectual property protection and digital multimedia data anti-counterfeiting

I. classification of digital watermarks

digital watermarks are also called digital watermarks. It is a technology that uses digital technology to hide images, audio, video, text and other objects directly in still images, moving images or other digital communication media. According to the different embedded media, it is mainly divided into image watermark, audio watermark, video watermark, text watermark and network watermark. Different from the traditional encryption system, the main purpose of the application of digital watermarking technology is not to restrict access to the media, but to ensure that the watermark in the media is not changed or eliminated, so as to provide the necessary proof information for the media. To understand the purpose of digital watermarking, first understand the classification of digital watermarking

1. According to the characteristics, digital watermarking can be divided into robust digital watermarking and fragile digital watermarking. Robust digital watermarking is mainly used to identify copyright information in digital works. It requires that the embedded watermark can withstand various common processing; Fragile digital watermarking is mainly used for integrity protection. Fragile watermarking must be sensitive to signal changes. People can judge whether the data has been tampered according to the state of fragile watermarking

2. According to the media attached to the watermark, the digital watermark with stable clamping force can be divided into image watermark, audio watermark, video watermark, text watermark and lattice watermark for three-dimensional lattice model

3. According to the detection process, digital watermarking can be divided into non blind watermarking, semi blind watermarking and blind watermarking. The non blind watermark needs the participation of the original data and the original watermark in the detection process, while the semi blind watermark does not need the original data. The detection of blind watermark only needs the key, not the original data and the original watermark. Generally, the robustness of non blind watermarking is relatively strong, but its application is limited by the storage cost. At present, most digital watermarks are blind watermarks

4. According to the content, the watermark can be divided into meaningful watermark and meaningless watermark. Meaningful watermarking refers to the encoding of a digital image (such as a trademark) or a digital audio segment; Meaningless watermark only corresponds to a serial number. If the decoded watermark is damaged due to attack or other reasons, people can still confirm whether there is a watermark through visual observation. But for meaningless watermarks, if the standard sample size is solved: 10 × ten × If there are several symbol errors in the watermark sequence after 55mm code, we can only determine whether the signal contains watermark through statistical decision

5. According to the purpose of the watermark

the digital watermark can be divided into bill anti-counterfeiting watermark, copyright protection watermark, tamper prompt watermark and hidden identification watermark

6. According to the location of the watermark, the digital watermark can be divided into time domain digital watermark, frequency domain digital watermark, time/frequency domain digital watermark and time/scale domain digital watermark

second, the characteristics of digital watermarking

digital watermarking comes from information hiding technology. It hides the marked information with specific significance in digital images, sounds, documents, videos and other digital files by using digital information processing methods and computer processing. It extracts the hidden watermark information by detecting and analyzing the digital files, and uses these watermark information to prove the creator's ownership of his works, And as the evidence to identify the authenticity of products and prosecute illegal infringement, digital watermarking has become an effective means to protect intellectual property rights and digital multimedia anti-counterfeiting. The reason why digital watermarking plays a great role in product anti-counterfeiting is that it has some remarkable characteristics. The main characteristics include the following aspects:

1 Fidelity

is also often referred to as invisibility, which refers to the degree to which watermark embedding leads to the change of host signal quality. Since the host signal is mostly multimedia data for people to watch, the watermark should have high fidelity, while increasing the security of the watermark itself

2. Robustness

refers to the survivability of watermark in the process of media data and processing. Various operations of media data will lead to the loss of host signal information, thus destroying the integrity of the watermark, such as compression, filtering, denoising, clipping, scaling and rotation, including some malicious attacks

3. Security

in the application, someone always wants to embed, detect or remove the watermark, and must restrict others to do the same, which is the security of the watermark. In order to achieve security, important information must be kept confidential, such as watermarks usually generated by using keys

4. Low error rate

even without any attack or other circumstances, the watermark cannot be detected or the probability of detecting the watermark is very small in 2013

5. Tamper resistance

refers to that once the watermark is embedded into the carrier, it is difficult for the attacker to change or imitate or tamper with it. But it is not easy to do this in copyright protection

Third, the general model of digital watermarking

digital watermarking is an information security technology developed in recent years. At present, there is no complete theory. Digital watermarking generally includes two main processes: embedding and detection. In order to make it more difficult for attackers to remove and destroy watermarks, most of the current digital watermarking schemes use encryption technology in embedding detection. Only those who master the key can detect and extract the watermark

1. Embedding watermark

embedding mainly solves the embedding algorithm, which is the core technology of digital watermarking, and the generation method of digital watermarking. The embedding process of digital watermark is shown in Figure 1: the system inputs the original data, watermark information and watermark key, and obtains the embedded watermark data through the embedding algorithm

2. Detection watermark

the detection process of digital watermark is the inverse process of embedding process. In the detection stage, the watermark is mainly extracted according to the algorithm. The detection process of digital watermark is shown in Figure 2: the system inputs detection data, watermark information or original data and watermark key, and obtains watermark information through detection algorithm

fourth, the application of digital watermarking in the anti-counterfeiting of digital products

the basic idea of digital watermarking is to add information as a mark to the original media data, which is closely combined with the original data and then transmitted together. At the receiving end, the computer watermark signal is extracted for digital signature, digital fingerprint, broadcast monitoring, content authentication, copy control and secret communication. Digital watermarking is regarded as the "last line of defense" against multimedia piracy. Therefore, from the perspective of watermarking technology itself, it has broad application prospects and great economic value

l. copyright protection

the concept and method of digital watermarking was first proposed for the copyright protection of multimedia data. With the development of computer and Internet, more and more works of art, inventions or ideas begin to be expressed in the form of multimedia data, such as digital photos, digital movies, music listening with MP3 player, computer painting, and so on. The multimedia data involved in all activities contain a lot of valuable information. Today, with the development of science and technology, it is easy to tamper with, forge, copy and illegally publish original works. Digital watermarking is just an effective means to solve this kind of "copyright problem". For example, in the past, painters used seals or signatures to identify the author of works. Today, he can add his name to his works through digital watermarking to complete the identification of copyright. Similarly, audio and video companies can also add the company's name, logo and other information to published tapes and CD discs. In this way, the copyright of multimedia data is protected by tracking the digital watermark information in multimedia data

2. Authenticity authentication

in addition to its application in copyright protection, digital watermarking technology is also very useful for the authenticity authentication of printed materials, electronic documents, etc., such as red headed documents issued by government departments. The traditional method of document authentication is to identify whether the paper, seal or steel seal of documents comply with specifications and standards, but its disadvantage is that whether the paper, seal or steel seal is easy to be forged. Using digital watermarking technology can effectively solve this problem. Digital watermarking can be used as an information carrier to add some information to the red headed document, so that the document not only has a seal or steel seal, but also has imperceptible digital watermarking information, which greatly increases the difficulty of document forgery

3. Copy protection

the copy problem of digital products is the fundamental problem it faces. Digital watermarking can be used to describe the data of digital products being copied, so as to control the data being copied or limit the number of copies, so as to achieve protection. For example, the secret digital watermark information in the CD data disk can conditionally control what kind of people can access the contents of the CD disk

4. Secure communication

digital watermarking technology can also be applied to secure communication of information. Because it is difficult for people to detect the existence of digital watermarking information in multimedia data, some important information can be hidden in ordinary multimedia data in the process of transmission, so as to avoid eavesdropping and monitoring by third parties

to sum up, compared with other printing anti-counterfeiting technology fatigue testing machines, digital watermarking has some special advantages, which are mainly reflected in the following aspects:

① low production cost. No special materials are needed, the original production process is not changed, and the cost is not increased, so the purpose of anti-counterfeiting can be achieved

② it is difficult to forge. Digital watermarking is a new technology studied in the field of anti-counterfeiting in recent years. Digital watermarking information has great concealment, and it is difficult to imitate

③ easy to realize. Using some special detection equipment and corresponding software can realize watermark embedding and detection and extraction

④ no interference. It does not interfere with other anti-counterfeiting technologies and means, forming a good compatibility, and then improving the anti-counterfeiting effect

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