Watermark (redirected from Spread Spectrum Watermarking)

watermark: see paper.

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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.

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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