When digital watermarking is applied to security traceability, packaging, bills, credit cards and document printing are all potential application fields. When used for copyright protection, the potential application market lies in e-commerce, online or offline distribution of multimedia content and large-scale broadcasting services. When digital watermarking is used to hide signs, it can be applied to medicine, cartography, digital imaging, digital image monitoring, multimedia indexing and content-based retrieval. In the authentication of digital watermark, the secure invisible communication of digital watermark on ID card, credit card and ATM card will be widely used in national defense and intelligence departments. The rapid development of multimedia technology and the popularity of Internet have brought a series of political, economic, military and cultural problems, and produced many new research hotspots. The following issues that have aroused widespread concern constitute the research background of digital watermarking. Copyright protection of digital works (such as computer art, scanned images, digital music, video and 3D animation) is a hot issue at present. Because it is very easy to copy and modify a digital work, and it can be exactly the same as the original, the creator has to use some methods that seriously damage the quality of the work to add copyright marks, and this obviously visible mark is easy to be tampered with.
-"Digital watermarking" uses the principle of data hiding to make the copyright mark invisible or inaudible, which does not damage the original work, but also achieves the purpose of copyright protection. At present, the digital watermarking technology for copyright protection has entered the preliminary practical stage. IBM has provided digital watermarking function in its "Digital Library" software, and Adobe has also integrated Digimarc's digital watermarking plug-in into its famous Photoshop software. But realistically speaking, the technology of digital watermarking products on the market at present is not mature, and it is easy to be destroyed or cracked, and there is still a long way to go before it is really practical. With the development of high-quality image input/output equipment, especially the appearance of color inkjet, laser printer and high-precision color copier with accuracy exceeding 1200dpi, it becomes easier to forge bills such as money and checks.
On the other hand, in the process of transforming from traditional commerce to e-commerce, there will be a large number of excessive electronic documents, such as scanned images of various paper bills. Even after the network security technology is mature, all kinds of electronic bills still need some non-password authentication methods. Digital watermarking technology can provide invisible authentication marks for various bills, which greatly increases the difficulty of forgery. -Information hiding technology can be widely used. As a certificate, everyone needs more than one certificate, which can prove personal identity: ID card, passport, driver's license, pass, etc. Proof of a certain ability includes: various academic certificates, qualification certificates, etc.
At present, China is facing huge business opportunities in the field of document anti-counterfeiting. Due to the lack of effective measures, "counterfeiting", "buying fakes" and "using fakes" have become the norm, which has seriously interfered with the normal economic order and adversely affected the national image. The authenticity of the certificate can be confirmed by watermarking technology, which makes it impossible to copy and copy the certificate. The identification information of data is often more confidential than the data itself, such as the shooting date, latitude and longitude of remote sensing images, etc. Sometimes the data without identification information can't even be used, but it is dangerous to mark these important information directly on the original file. Digital watermarking technology provides a way to hide the logo. Logo information is invisible in the original file and can only be read by a special reader. This method has been adopted by some foreign public remote sensing image databases.
-In addition, data tampering tips are also a very important job. The existing signal splicing and mosaic technology can achieve "grafting" without being known, so how to prevent tampering attacks on image, audio and video data is an important research topic. Tampering hint based on digital watermark is an ideal technical way to solve this problem, and whether audio-visual signals have been tampered with can be judged by hiding the state of watermark. The information hiding technology that digital watermarking relies on not only provides a non-password security approach, but also triggers a revolution in information warfare, especially network intelligence warfare, resulting in a series of novel combat methods, which has attracted the attention of many countries.
Network intelligence warfare is an important part of information warfare, and its core content is to use public networks to transmit confidential data. So far, academic research in this field has failed to break through the thinking mode of "file encryption". However, encrypted files are often confusing and easy to attract the attention of attackers. With the wide application of network multimedia technology, using public network for secure communication has become a new idea. By using the redundancy of digital audio-visual signals relative to human vision and hearing, information can be hidden in various time (space) and transform domains, thus realizing covert communication.