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The information to be embedded in a signal is called a digital watermark, although in some contexts the phrase digital watermark means the difference between the watermarked signal and the cover signal. The signal where the watermark is to be embedded is called the host signal. A watermarking system is usually divided into three distinct steps ...
It is a shaded watermark first used in 1848 that incorporates tonal depth and creates a greyscale image. Instead of using a wire covering for the dandy roll, the shaded watermark is created by areas of relief on the roll's own surface. Once dry, the paper may then be rolled again to produce a watermark of even thickness but with varying density.
In the fields of physical security and information security, the high-water mark for access control was introduced by Clark Weissman in 1969. [1] It pre-dates the Bell–LaPadula security model, whose first volume appeared in 1972.
A watermark stored in a data file refers to a method for ensuring data integrity which combines aspects of data hashing and digital watermarking. Both are useful for tamper detection , though each has its own advantages and disadvantages.
A Watermark for data synchronization describes an object of a predefined format which provides a point of reference value for two systems/datasets attempting to establish delta/incremental synchronization; any object in the queried data source which was created, modified, or deleted after the watermark's value will be qualified as "above watermark" and should be returned to the client ...
Yellow dots on white paper, produced by color laser printer (enlarged, dot diameter about 0.1 mm) Printer tracking dots, also known as printer steganography, DocuColor tracking dots, yellow dots, secret dots, or a machine identification code (MIC), is a digital watermark which many color laser printers and photocopiers produce on every printed page that identifies the specific device that was ...
Audio watermark, techniques for embedding hidden information into audio signals; Watermark (data file), a method for ensuring data integrity which combines aspects of data hashing and digital watermarking; Watermark (data synchronization), directory synchronization related programming terminology; Watermarking attack, an attack on disk ...
In such a case, the technique of hiding the message (here, the watermark) must be robust to prevent tampering. However, digital watermarking sometimes requires a brittle watermark, which can be modified easily, to check whether the image has been tampered with. That is the key difference between steganography and digital watermarking.