Source: "Indian Art" 2003 No. 10
Zhou Yanqiong, pen name Zhou Jie, Sichuan Chengdu, Master, senior engineer, has published more than 20 papers.
Tampers suggest that watermark is a fragile watermark, the purpose is to identify the integrity and authenticity of the host signal. The purpose of hidden marking watermark is to hide the important label of confidential data to limit illegal users.
Follow the hidden position of the digital watermark, it can be divided into time / scale domain digital watermarks. When the digital watermark is overlay the watermark information directly in the signal space, the frequency domain, the time / frequency domain, and the time / scale domain, respectively, in the DCT transform domain, the time / frequency transform domain, and the wavelet transform field hidden water printing. .
According to the media attached to the watermark, it can be divided into images, audio, video, text, and grid watermarks for the three-dimensional grid model. With the development of digital technology, there will be more types of digital media, and it will also generate corresponding watermarking techniques.
Digital watermark application prospect
In recent years, digital watermarking technologies have continued to expand new application areas. The application in printing and anti-counterfeiting is the current new topic. The relevant information shows that about 500,000 people have been injured in fake documents or fake documents, direct or indirect loss of about $ 750 million each year. Traditional anti-counterfeiting watermarks makes the criminals organically multiplied due to imperfect technology. Digital watermarking technology is a pathogeneration, using digital signal processing related techniques, taking trace data in media data works. After the watermark technology is embedded, the original media data does not have changed, nor does it affect the normal use of the original data. People cannot perceive watermarks from the surface, only dedicated detectors or software can detect. It is extremely widely used in various product printing packaging, trademarks, invoices, checks, securities anti-counterfeiting, digital media copyright protection.
Currently, digital watermarking technology for copyright protection has entered the preliminary practical phase. IBM provides digital watermarking features in its "Digital Library" software, and Adobe also integrates Digimarc's digital watermark plug-in in its famous Photoshop software. However, digital watermark products on the market are still immature, it is easy to be destroyed or cracked, and there is still a long way to go.
According to US official report, only 50 million US dollars in 1997, with high-precision color printers with high-precision color printers accounted for 19%, this figures were 9.05 times in 1995. Currently, both US, Japan and the Netherlands have begun to study digital watermarking technologies for ticket security. The Media Labs of the Massachusetts Institute of Technology are entrusted by the US Treasury. It has begun to add unique, unacceptable digital watermarks in each image of the color printer, and the copy machine output. If you need to judge the watermark from the scanning ticket Quickly write authenticity.
US Digimarc took the lead in launching the world's first commercial digital watermark software, and later integrated the software into Adobe Photoshop and Corel Draw image processing software. Subsequently, a series of digital watermark products have been introduced, and the Mediabridge technology develops a new way to access the Internet, and hidden invisible digital watermarks in magazine advertising, product packaging, directory or even various types of notes. The user can bring the user directly to the network site associated with the printed image content, eliminating the user to tap the keyboard and click the mouse. For example, the magazine that will be placed in the network camera, the media bridge technology will show the information about the advertising company's homepage and advertisements on the computer, free of the process of searching online with the browser online. "Brand Protection" technology can be confirmed in any part of the product circulation chain by adding confidential features to any link, identifying the original and copy, preventing product forgery, and can track products by supply chain Circulation. "Secure Document" technology adds Digimar's watermark features to confirm the authenticity of the document, prevent unauthorized documentation from copying and confirming the authorization application of the original document.
During traditional business □ E-commerce transformation, there will be a large excessive electronic document, such as scanning images of various paper tickets, even after network security technology matures, various electronic bills also need some non-password certification. the way. Digital Watermarking technology can provide invisible authentication marks for various tickets, which greatly increases forged difficulty.
Research on Digital Watermark in China
In China, the relevant department researchers are stepping up the research work of digital watermark printing anti-counterfeiting technology, such as Dalian University of Science and Technology has achieved effective research results in digital watermarking and anti-counterfeiting technologies. Its technology can be implemented in a printed image to complete the automatic detection of digital watermarks in the printed image by scanners and dedicated software, which adapts to a variety of models of printers and scanners.
Digital technology and the development of the Internet are changing the carrier and way of cultural communication methods. It is not enough to complete data encryption, authentication and protection by traditional password technology. Digital watermarks have an irreplaceable role in copyright identification, network security, hidden security, tampering tips, data security, etc., which will bring huge commercial profits for commercial, financial, military and personal consumption.
I believe that digital watermarks will play a huge role in socio-economic development, and can produce considerable economic benefits. It is a matter of urgent to develop independent core software and products as soon as possible, so that China can in the face of the opportunities and challenges to join WTO. The research, application and industrialization development process is in unbeaten.
