Source:
(Computer World News
First
44
period
B3
,
B5
) Anti-counterfeiting technology is a class of special technologies for protecting items that make it difficult to be forged, which must be unique and difficult to fake, and must also be accurately identified. Anti-counterfeiting technique must first have the onlyness, so that the corresponding technology cannot be obtained from elsewhere; second, it is necessary to have difficulty for fake, because for the forked person, what is first thought of worth investing a lot of manpower and material power, whether it is quite long? time. Moreover, the existence and development of anti-counterfeiting technologies must be attached to the demand for protected objects, and the ultimate goal of anti-counterfeiting technologies is to defeat the fake, making it unable to implement forged purposes. Therefore, it is necessary to integrate anti-counterfeiting techniques for anti-counterfeiting performance as the core technology of the anti-counterfeiting system, and the technology should be able to accurately use the supporting instrument. For important anti-counterfeiting product users, multiple performance techniques should be used to use to achieve more effective anti-counterfeiting purposes. The combination of anti-counterfeiting technologies is: the anti-counterfeiting secret of sensory detection and the secret of automatic automatic detection of the machine; the combination of anti-counterfeiting features and dark anti-counterfeiting features; set the anti-counterfeiting impofer group, form a multi-layer anti-counterfeiting structure, to meet the different Personnel's anti-counterfeiting authentication is divided into different levels. Choose a research and development project for anti-counterfeter technology, to meet the anti-counterfeiting application requirements, choose those anti-counterfeiting performance, both the unique technique that is difficult to be used by peers, but also to meet the following conditions: ◆ Use the technology to produce anti-counterfeiting products It should be more prone to mass production, and the product consistency is good; ◆ It is best to derive a variety of anti-counterfeiting products, but the anti-counterfeiting products that are not connected to each other; ◆ Method using simple replication cannot be used; ◆ It is best to have more than two Relatively independent research and production steps to facilitate restrictions and management; ◆ Products produced with this technology should have unity; ◆ The anti-counterfeiting features of the feel identified should be easy to distinguish and difficult to simulate similar features, and have machine identification Features, guarantees that the use of the supporting identification instrument can accurately perform authenticity; ◆ The anti-counterfeiting product produced by this technology should be able to support the protected target, will not be completely transferred; ◆ Produced products It should have a lower cost; ◆ The price of anti-counterfeiting products and supporting instruments is reasonable, and the entire security system has a high function. The emergence of digital watermarking technology has brought new opportunities to the development of anti-counterfeiting technologies. Its unique features completely updated traditional anti-counterfeiting technological concepts. Digital watermark technology has a variety of categories. It can be divided into robust watermarks and fragile watermarks by action. The former is primarily applied to the logo copyright information in digital works, which requires embedded watermarks to resist common editing processing and lossless compression; the latter is mainly used for integrity protection, and determines whether the signal is tampered with. According to the carrier of the watermark, the digital watermark can be divided into image watermark, video watermark, audio watermark, text watermark, and printing watermark. If the digital watermark can be divided into clear watermark and blind watermarks according to the detection method. Techniques that require the original data during the test, referred to as Ming Watermark, strong robustness; techniques that do not require the original data during the detection process are called blind watermarks. Digital watermarks can be divided into content watermarks and markers watermarks. The content watermark means that the watermark can still be judged after the attack is damaged; the marking watermark refers to whether the signal is defined by the detection determination. When categorized by use, digital watermark can be divided into copyright protection watermark, tampering suggests watermark, banned watermark, hidden marking watermark, print digital watermark, etc. Digital watermarks have the following main characteristics: The unknown multimedia information does not change its perceptual effect after adding watermark, and the watermark is not feeling under the usual perception conditions. This is the most basic feature of digital watermark, that is, multimedia information embedded after the watermark, the number The changes and distortion of information should be lower than the perceived threshold. If an image is added to the watermark, it does not feel that the image has any changes in the visual, even if it is not detected by natural light or other outer light source irradiation, it does not detect what is different from the original image.
Robust refers to the watermark information in multimedia to resist various destruction in the application, such as digital signal processing techniques, including noise, filtering, and lossy compression. Safety Digital Watermarking systems use one or more keys to ensure security to prevent modification and erase watermarks. Information is hidden in multimedia content, not lost due to file format, and unauthorized watermarks cannot be detected. Since the similarity digital watermark is still returned from the original data, hidden watermarks can still be restored from the original data, and the original image is not required during the recovery process, which requires the watermark algorithm itself with self-similarity. It is also conceivable that the watermark information is distributed in many samples of the carrier data, and the watermark can be restored using small part of the data. Applying digital watermark printing anti-counterfeiting technologies, not only makes copyright owners such as trademarks, but also enhances users' trust in their goods, maintaining the brand image and economic benefits of their products, but also protects all kinds of important documents Technical measures on a new step. Digital watermark technology is used in printing or printing with many features compared to applications in the Internet. From a technical point of view, when designing software and algorithms, there is a need for better robustness and anti-aggressiveness, but also need to meet some special properties: Visual invisibleity is visually not visually missed. Watermark, and it does not affect the visual quality of the original print. Using the software into a digital image in a digital image, it is easy to meet visibility on the network; for printing and anti-counterfeiting, this feature is expressed in various resolutions when using print or printing equipment. Watermark The watermark cannot be displayed due to the reduction or elevation of the resolution. Machine reading method is an assembled mode, which can be used to complete hidden watermarking, and can also cooperate with database support and network authentication as needed. Digital watermarking algorithm for nonlinear robustness to achieve software must resist A / D and D / A conversion, i.e., add digital watermarks to the computer, and print or print the images containing watermarks through the printer. After flowing, the image is input to the computer by photoelectric detection, which includes nonlinear quantization distortion and space aliasing. Robust and visual invisibility are contradictory. Resistance to rotation, scaling, and cutting in the printing process, to generate a proportional change in zoom. During the detection process, since the position placed in the printing is not correct, rotation and shear variation may occur. Digital watermarking algorithm needs to resist gamma correction and color distortion during A / D and D / A conversion. Printing and printing images In the process of retract, color distortion is produced due to the aging of the print. File format transformation is also often encountered, such as BMP, TIFF, CYMK, etc. format switching. The digital watermarking algorithm for confidentiality is not only visually can't be visually, but also the encoding method and location of the watermark is considered. If combined with the cryptography, it will play a double encryption. The watermark capacity of watermarking capacity and robustness is contradictory. The increase in watermarking capacity will bring robust to decline, which has an impact on invisibility. In order to resist various transformations, watermarks typically need to add multiple times in the image, and when the watermark capacity is large, the result will result in a reduction in repetition, and the robustness will lead to test results. Unreliable. User-oriented digital watermark systems can be designed according to user needs, namely the user's custom system. Visual invisibility is the foreigner in digital watermarking technology, which is essentially a human visual redundancy or insemination, so watermark research based on sensing theory is very necessary. A perceived watermark is a digital watermarking technique utilizing perceptual information in watermarking processing. The current perceived watermark is mostly used to use the human-eye-based modulation transmission function (MTF) frequency sensitivity, in order to improve the robustness of digital watermark, it is necessary to establish a more complete human visual model suitable for watermarking.
