Anti-counterfeiting new technology: digital watermark (two)
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
Looking at the research work of digital watermarks on the anti-counterfeiting of printed matter in the past, there is not much information available. The existing digital watermarking techniques based on halftone images generally have the following types:
1 A digital watermarking technique based on a halftone image is to embed invisible digital information into a halftone image, and to obtain embedded watermark information by scanning the halftone image and implementing a certain extraction algorithm. One of the techniques is to use two different dither matrices to produce sequential dithered halftone images. Due to the different statistical properties of the two different dither matrices, it is possible to detect the presence of a watermark.
2 The second technique uses vector quantization to embed the watermark into the least significant bit (LSB) of the error-diffusing halftone image.
3 The third technique is to hide the watermark data in a random position in the sequential jitter or error diffusion image, and to change the pixel values of these random positions by self-locking or paired locking techniques to realize information hiding.
4 The fourth technique is to hide the watermark data in the error diffusion image, and use the error diffusion method to reduce the image distortion caused by the hidden data, so that the image obtains a good visual effect. In the above method, although the hidden data itself is an image, these algorithms do not provide a method of directly observing these hidden images on a halftone image.
5 Another technique is to embed hidden visual images into two or more halftone images. When the two images are superimposed, the hidden images can be directly displayed. One such technique is to use a random screen or a conjugate screen to embed hidden information into a halftone image. Because of the nature of conjugates, when two halftone images are stacked together, the hidden information will be presented (the effect is shown in Figure 4).
6 Another technique is a halftone digital watermarking technique that considers noise balance error diffusion and alternately uses different error diffusion kernel spreads.
7 Some people have proposed a direct binary search (DBS) method using a human eye vision system model based on halftone technology. DBS is used for the design of halftone images for optimal visual quality and watermark detection.
3, the results of the discussion
We use Matlab6,5 programming simulation to achieve 256-level gray image lena error diffusion screening (using Jarvis-Nike error diffusion kernel) to obtain halftone images, and use different digital watermark embedding algorithms to obtain watermark information respectively. Halftone image.
The watermark embedding technique used is to hide the watermark data in a random position in the error diffusion image (the position is determined by the key), and to change the pixel values of these random positions by self-locking to realize information hiding. The obtained watermark-containing halftone image is compared with the original Iena halftone image, and it can be seen that equivalent to adding some noise to the original image. When the embedded watermark information is not large, it is not within the contrast range of HVS. Change its visual effects. The watermark embedding technique used is to embed the watermark information into the original halftone image according to the characteristics of the original halftone image and the watermark image to obtain a halftone image containing the watermark information. When the obtained image is superimposed with the original halftone image, The watermark image can be reproduced.
Under the experimental conditions, the obtained image is printed, scanned, and preprocessed, and the corresponding watermark image can be extracted according to the corresponding watermark extraction algorithm. In the experiment, in addition to using the binary image in the figure, we also used the text, Wuhan University emblem and so on to get satisfactory results.
The mediabrldge technology pioneered by Digimarc in the United States in 1995 was integrated into Phot0Sh0P and CorelDraw image processing software as a plug-in.
Subsequently, a new way to open up the Internet was introduced – by hiding invisible digital watermarks in magazine ads, product packaging, catalogs and even various types of notes. By placing these traditional media in front of a webcam, users can take the user directly to a web site associated with the printed image content and display information about the product on the computer. The VerlData family of software uses invisible watermarks to prevent trademark piracy and counterfeiting, piracy and unauthorized changes to important documents. The SafePaper software designed for printing documents in Switzerland can be embedded in Microsoft Word software. It hides the watermark information (such as the trademark patent name amount, etc.) into the printing paper to prove the authenticity of the document. The Japanese Research Laboratory has proposed using data hiding as a solution to identify the source of digital photos, confirm the integrity of digital photos, determine whether photos have been tampered with, and locate tampering.
Researchers in relevant departments in China are stepping up research on digital watermark printing anti-counterfeiting technology. Digital watermark anti-counterfeiting printing technology can realize digital watermarking in printed images, and can automatically detect digital watermarks in printed images through scanners and special software. ASSureImageMark2, an image digital watermarking software with independent intellectual property rights, 0: Printing and printing digital watermarking technology has been commercialized. It indicates that the research on digital watermarking technology in China has entered a substantive stage, and the gap between its R&D and application level and the international advanced level has gradually narrowed.
The most new technology, digital watermarking, is a new direction in the field of printing. We believe that digital watermarking technology will play an increasingly important role in the field of anti-counterfeiting printing, and will bring considerable economic benefits. And social benefits. However, we should also see that the digital watermark products used for anti-counterfeiting of printed materials on the market are still immature in technology, and there is still a lot of research work to be done.