Source: - Bo Xiaochen Shen Lin Cheng Changwensen
---- Although the study of digital watermarking technology is only a few years, its software industry has considerable
scale. As early in 1995, the research of digital watermarking technology has just begun, and the US Digimarc Company has
First introduced the world's first commercial digital watermark software, and then integrate the software into Adobe in the form of plug-in.
Photoshop 4.0 and Corel Draw 7.0. The commercial speed of digital watermarking technology is so fast, from one side
It reflects its urgent market demand.
market expectation
---- Digital technology and the development of Internet are changing the carrier and way of cultural communication, digital books
The new concepts such as the museum, online issuance, etc., digital products such as MIDI, CD, VCD, DVD, MP3 make people feel
Pick up. Digital watermarking technology is in data only by crypt code technology is encrypted, authentication, and protection of multimedia data.
Safety has an irreplaceable position.
---- Different from military, financial fields, digital audiovisual products are publicly sold, and the dealers are concerned about theft.
The version is not a stealing. Copyright means interest, copyright identity has also become the largest market for digital watermarking software.
Taking DVD as an example, involving dozens of IT companies, including IBM, NEC, Sony, including IBM, NEC, Sony
industry.
---- Network Security is a hot topic in recent years, and the watermarking products that are not tampered with the watermarks have begun.
The open angle and there is no doubt that will become a new growth point of digital watermark software.
---- Advanced technology is often applied to military and national security fields, and digital watermarking technology is no exception.
The US Army Lab is one of the first institutions for digital watermarking research, and the concealed identity of various military video data is
Tampering Tips is a digital watermark application research project that has been disclosed. As a method of writing a digital era, for hidden
Communication's large data volume information hidden technology has also attracted attention from Chinese intelligence departments. Digital watermarks have become a national defense
It will bring huge business profits in need. In addition, digital watermark is becoming a digital works.
The pet, its potential market as an individual consumer software is also ignored.
Software classification
---- From the technical statement, the current digital watermark software can be divided into two categories: time (empty) domain watermark software and change
Change the field watermark software.
---- 1. Time (empty) Domain Digital Watermark Software
---- So-called (empty) Domain Digital Watermark refers to the sound directly to the random sequence generated by the key,
As the video signal as a watermark. Since the energy of the embedded signal is very low, it will not be observed by the visual and auditory observation.
feel.
---- Common (empty) domain digital watermark technology has two types of LSB and extended spectrum. The LSB method is to use watermark
It is an early digital watermarking technology directly embedded in the minimum effective bit of the original signal indicating the data. obviously,
The LSB method has certain requirements for signals to be added to the watermark. As an example of image, if the original palette is not connected
Continued, the LSB method leads to a significant color distortion. Therefore, this type of software generally recommends that the user has continuous
The grayscale or true color image of the palette. For index color images, generally transform to true color space to hide water
Print, thus requiring the original color type of color not too much, otherwise it will lose watermark when transforming the returning color from the true color space.
information.
---- The spread spectrum hidden method on the time and space is to modulate the watermark information into a similar noise by the spreading code.
The energy of this signal is spread on the entire frequency band, which is difficult to recover through frequency domain filtering. This method is actually expanded
Software implementation of the communication system.
---- The advantage of the digital watermarking technology in the spatial domain is the hidden data volume, and can be based on the local
Adaptation. Its disadvantage is that it is too fragile, common signal processing, such as scaling, shearing, etc.
To destroy the watermark. In addition, this type of software is related to the specific file format, and the sound image file processed by such software is not
It is possible to perform loss.
---- 2. Transform Domain Digital Watermark Software ---- Transform Domain Watermark Software First Make the original image or sound signal DCT or wavelet transform, in the transformation
The watermark information is embedded on the domain, and then the reverse transform is output. When the watermark is detected, the signal should be carried out accordingly.
Transform, then detect watermarks by correlation operations.
---- Digital watermark on the DCT transform domain has strong robustness, which can be deformed against various signals. due to
JPEG, MPEG and other data compression methods are also operated on the DCT transform domain, so DCT transform domain digital watermark has
With the benefits of resistance to loss compression. However, the DCT transform domain watermark method cannot be made to the image, sound and other signals.
The content of the content is therefore often caused significant damage to the characteristics of image brightness.
---- Digital watermark method on wavelet transform domain has the advantages of time and space domain methods and DCT transform domain methods,
A technique that has both adaptive functions, and robustness, its disadvantage is that the amount is large.
development trend
---- Digital Watermarking software has a very fast development, initial only as an insert of image processing software, and now
It has begun to develop to large commercial software, showing the development trend of internet, multi-technical integration, main
It is reflected in the following aspects:
a .. Combined with intelligent technology, develop watermarking Agent and automatically track copyright marks.
b .. E-commerce, providing server-side integrity protection and client data authentication.
C .. Establish a Watermark Certification Center to provide a variety of online services.
d .. Develop digital work-on-sales system based on digital watermarking technology, providing complete safety and copyright
protection mechanism.
e .. Provide streaming-based digital watermark products for various payment plans.
f .. Digital watermark is developed for a broader digital media such as three-dimensional animation, digital map, etc.
Safety protection products.
g .. combined with password technology, especially digital signature technology, construct a comprehensive data security system.
H .. Construct a special person to identify watermarks using various biometric technology (such as fingerprint, retinal).
---- Digital Watermarking Software as new things in the field of data security, high technical content and strong
The vitality, and it also gab to make a huge business opportunity. We have reason to believe that there will be more and more people's insight.
Go to the research and industrialization process of digital watermarking technology.
