watermark

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watermark:

see paperpaper,
thin, flat sheet or tissue made usually from plant fiber but also from rags and other fibrous materials. It is used principally for printing and writing on but has many other applications. The term also includes various types of paperboard, such as cardboard and wallboard.
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Watermark

 

a picture in a piece of paper, visible when the paper is held up to the light; it is formed during the process of making the paper.

Watermarks began to appear in Europe in the 13th century, and in Russia in the second half of the 17th century. The study of watermarks and the determination of the exact place and time of the making of a piece of paper are very important for the correct interpretation of a source.

Since 1723, Russia, following the example of other European countries, impressed watermarks on stamped paper (a depiction of the state coat of arms and the words“stamped paper”) in order to avoid counterfeiting of official documents and currency. Watermarks are usually made on paper at precise intervals, or they cover the whole field of the paper in the form of a repeated drawing or pattern. They can be used to distinguish genuine money, valuable papers and documents, and stamps from counterfeit items. Watermarks are also used as a means of ornamenting paper. The imprinting of watermarks is usually done with a dandy roll or with cylinders of a cylinder paper-making machine on a wet web of the paper.

N. M. BOKAREVA

watermark

[′wȯd·ər‚märk]
(graphic arts)
A localized modification of the structure and opacity of a sheet of paper so that a pattern or design can be seen when the sheet is held to the light.

digital watermark

A pattern of bits embedded into a file that is used to identify the source of illegal copies. For example, if a digital watermark is placed into a master copy of an audio CD or DVD movie, then all copies of that disc are uniquely identified. If a licensee were to manufacture and distribute them in areas outside of their authorized territories, the watermark provides a trace.

The watermark developer has to find creative ways of altering the file without disturbing it for the user. It is difficult to embed a watermark within an ASCII file, which is just raw text. However, it is relatively easy to alter a few bits within audio, video and image formats without making a noticeable difference on playback or display.


WinZip's Watermark Function
The popular WinZip utility performs numerous functions beyond simply encrypting a file. This is the dialog showing options for adding a digital watermark to certain image files. See WinZip.
References in periodicals archive ?
Thus, entropy is applied to improve the robustness of watermarking.
A decoder in a watermarking system extracts the hidden binary sequence from a set of observed complex wavelet coefficients.
Pun, "Feature extraction and local Zernike moments based geometric invariant watermarking," Multimedia Tools and Applications, pp.
Araghi, "A Survey on Digital Image Watermarking Techniques in Spatial and Transform Domains," in Proceedings of the International Journal of Advances in Image Processing Techniques- IJIPT, vol.
This research focuses on a novel reversible watermarking scheme for medical images with blind recovery (no additional information needed) on receiver side.
Muzaffar, "Novel technique for capacity maximizing in digital watermarking using fuzzy rule base," Journal of Intelligent & Fuzzy Systems: Applications in Engineering and Technology, vol.
A novel digital watermarking scheme for medical images which offers robustness to the watermark information and fragility to the host medical image based on chaotic key, hash function, product codes, and RNS is proposed.
Sadawarti, "Adaptive digital image watermarking for color images in frequency domain," Multimedia Tools & Applications, vol.
The watermarking algorithms mentioned in [1-24] are used single watermark information and inserted into host medium.
In the presented watermarking scheme, the three mutually dependent channels of a color image are first decorrelated, so that alteration in any one of them has no adverse effects on others.
Section 4 introduces watermarking protocols and their security problems, together with the most important design challenges that such protocols have to face to be used in the current web context.
Another modification on the LSB watermarking scheme compares two bits from the cover image and the secret message.