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The application of ordinary watermarks and digital watermarks in print anti-counterfeiting

when you mention watermarks, you may immediately think of the watermark pattern in RMB. When you talk about digital watermarks, many people may not have a clear understanding. In fact, watermarks in RMB are only ordinary watermarks. Digital watermarks are very different from ordinary watermarks. They all play a great role in anti-counterfeiting, copyright authentication protection and other fields

1 ordinary watermark

ordinary watermark is also called traditional watermark, which is formed in the process of papermaking. When the paper is copied, when the paper pages are just intertwined and have moisture, a device with special patterns and words is used to displace part of the organization of the wet paper pages, adjust the thickness of the paper layer, and form different patterns and words. When the paper is dry, these patterns and words called watermarks can be seen when you look in the light. Watermarks are also divided into black watermarks, white watermarks, yin-yang watermark and so on. The most common is the black watermark, which is relatively simple. Add a watermark device with graphics and text on the paper machine, and the graphics and text are recessed. When the paper is formed, more pulp is attached to the paper than the other parts of the paper, so that the thickness of the watermark graphics and text part of the paper is greater than that of the other parts of the paper. In contrast to the black watermark, the white watermark is convex at the image and text. When the paper page is formed, the image and text part of the watermark has less pulp and less thickness than other parts of the paper. Yin Yang watermark is a combination of black watermark and white watermark, but it is rarely used

ordinary watermarks have been formed in the process of papermaking. If forged watermarks are printed with white ink on printed matter, it is easier to identify them. Moreover, the production of watermark paper is strictly controlled in various countries, so it is difficult to imitate watermark paper. In today's era of advanced science and technology, ordinary watermarking is still recognized by anti-counterfeiting experts all over the world as an effective anti-counterfeiting technology, which continues to be adopted and developed by all countries. The paper used in banknotes, various bills and certificates in most countries is added with their own different watermark patterns and words

after all, ordinary watermarks can be seen with our naked eyes. With the development of science and technology, the means of counterfeiters are also improving. No one can guarantee that they will not be used by counterfeiters one day. Therefore, it is necessary to design a watermark that we can't see with our naked eyes, which is what people call digital watermarking technology

2 digital watermarking

digital watermarking comes from information hiding technology. It uses the method of digital information processing and computer processing to hide the marked information with specific significance in digital files such as digital images, sounds, documents and videos. It extracts the hidden watermark information through the detection and analysis of digital files, These watermark information is used to prove the relevant laboratory rights of the creator to his works, which are widely used in industrial departments such as machinery, metallurgy, petroleum, chemical industry, building materials, construction, aerospace, shipbuilding, transportation, colleges and universities, scientific research institutions, and as evidence to identify the authenticity of products and prosecute illegal infringement, so that digital watermarking has become an effective means of intellectual property protection and digital multimedia anti-counterfeiting

digital watermarking technology has its own inherent characteristics. Its features are as follows:

invisibility. When ordinary people use the carrier data containing watermark, it is difficult to determine the hiding position of the watermark. The change of the carrier data induced by embedding the watermark information and adjusting the scope of the oscilloscope (v/div) to the maximum is not easy to detect for the observer's visual or auditory system

provable. The hidden watermark information should provide reliable evidence for the attribution of the product to be protected. A good watermarking algorithm should be able to embed the necessary information (such as product logo or meaningful text) into the protected object, and extract these information when necessary, as undisputed evidence to identify the product

reliability. Reliability means that the watermark should be able to withstand a certain amount of physical and geometric distortion, including intentional (such as malicious attacks) or unintentional (such as image compression, denoising, printing 3, low shrinkage nylon modified materials, scanning and copying, size transformation, etc.). After these operations, a robust watermarking algorithm should still be able to extract the embedded watermark from the watermark carrier or prove the existence of the watermark. If the watermark is forcibly removed, the carrier data will inevitably change greatly, and the quality will decline seriously, so that it cannot be used

digital watermarking technology hides a certain amount of information into the carrier data through special embedded software. When carrying out detection and identification, as long as the carrier data is input into the computer and detected and extracted with special extraction software, these two processes do not require special instruments and equipment, and there will be no additional cost. Considering that the technology used in the current printing anti-counterfeiting will increase the cost, people began to study the application of digital watermarking in the printing anti-counterfeiting, hoping to achieve a reliable anti-counterfeiting effect without increasing the cost, The research shows that this method is feasible. Next, we will introduce the anti-counterfeiting application of digital watermarking in printed matter in detail as follows

with the image as the carrier, when the image to be printed is made, the watermark information determined by the construction of the project is hidden in the image through the watermark embedding software. The original image and the image embedded with the watermark are visually indistinguishable, and the appearance is almost the same, and then the image is output, plate making, printing, to get the printed matter. During the detection, the image in the printed matter is scanned into the computer to get the digital image. The digital image is first corrected and denoised, and then the watermark information is detected with the extraction software. The authenticity of the printed matter is judged according to the extracted watermark information. For counterfeiters, this method is difficult to forge, because the hidden information can't be seen. They don't know the method used to embed the watermark, and they don't know what the embedded information is, so they can't imitate and hide the hidden information. They can only imitate the words and images of the printed matter they can see. In this way, the forged printed matter doesn't contain watermark information, and the watermark can't be extracted during detection, Thus, the authenticity can be distinguished

from the above introduction, it can be seen that digital watermarking has its own technical advantages compared with other printing anti-counterfeiting technologies, which are mainly reflected in the following aspects:

1. Low anti-counterfeiting cost: there is no need to add special materials, do not change the original printing production process, the printing cost remains unchanged, and do not need to invest a lot of money at one time, which can easily realize high-tech anti-counterfeiting and copyright protection

2. It is difficult to forge: digital watermarking has high scientific and technological content, and it is a relatively new technology in the field of anti-counterfeiting. The watermark information has great concealment, and encryption technology can also be used, which is difficult to forge

3. fast technology upgrading: according to the product characteristics, a set of special software is designed and produced for each set of products, and the update and upgrading of anti-counterfeiting information is very convenient

4. easy to implement: watermark embedding, detection and extraction can be realized by scanner or special detector, plus supporting software

5. good compatibility: it does not interfere with other anti-counterfeiting means and copyright protection technology, and is compatible with each other, which can further improve the anti-counterfeiting effect

3 summary

ordinary watermarks are added to paper in the process of papermaking. This kind of watermarked paper is usually used to make important bills and certificates. In order to ensure the excellent performance of paper, there are high requirements for raw materials used in papermaking, which leads to the high price of watermarked paper. Moreover, ordinary watermarks can be seen by our naked eyes and may be forged by counterfeiters through various means. However, due to the good control of watermark paper by the state, ordinary watermark is still a widely used anti-counterfeiting means of paper prints. Compared with ordinary watermarks, digital watermarking technology has the technical advantages of safety and reliability, low cost, difficult to forge, strong adaptability and so on. It is gradually being paid attention to in the anti-counterfeiting of printed materials. Many research institutions and companies at home and abroad have carried out extensive research on it. Digital watermarking technology has been used in the anti-counterfeiting of local tax invoices in individual cities in China. If ordinary watermarks and digital watermarks are applied to the anti-counterfeiting of printed matter together, and they can play their own anti-counterfeiting role together, it will make printed matter more difficult to forge. I believe that with the continuous improvement of research level and the continuous development of the anti-counterfeiting market of printed matter, they will play an increasingly important role in the field of anti-counterfeiting

source: Xinhua Printing Author: Liu Quanzhong, Guo Shuguang, Wang Xia