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DOCUMENT WATERMARKING
Most people are familiar with the watermarks that they see in banknotes or on checks. These are designs that are put into the paper on which the documents are printed, and are normally used to prevent people from being able to make fake copies.
These are not the only types of watermarks that can be used to protect documents, and LockLizard allow you to add a number of different types of watermark to visible images and printed documents protected by LockLizard.
Watermarks may be static or dynamic, and they may also be copy preventing or copy revealing. Typically, a combination of these is used to provide suitable document protection.
Static watermarks are those which do not change regardless of who opens and processes the watermarked document. They behave in a similar way to that on the banknote. It doesn’t matter who gets the banknote, the watermark is the same. Static watermarks may be used to prove the authenticity of the document, or to make it difficult to produce another document and then pretend it is authentic. They are also used to identify the owner (or copyright controller/ or the document. Static watermarks may be used so that when a document is copied, a previously ‘hidden’ watermark is revealed and that shows that the copied document is not an original.
Dynamic watermarks in the physical world were created by affixing a seal to a document, or stamping it (as a bank or post office does with documents, even today). These kinds of watermarks are used to identify the individual associating themselves with the authenticity of the document. In PDF document watermarking terms these are watermarks that are added at the time of viewing or printing that identify the individual/enterprise that is using the protected PDF document.
Dynamic watermarks may be used as a form of copy preventing, because the individual allowing the watermarked document to be copied is also associating their own identity with it, and they most likely do not want to be identified as the source of copied materials.
Static watermarks may also be used for copy preventing. In this approach, a diffraction pattern (sometimes referred to as a Moire fringe pattern) is used. Whilst the human eye is subtle enough to be able to ignore the pattern, mechanical devices such as scanners and photocopiers become confused by the presence of the pattern and produce substandard copies or cannot convert the graphic scanned image back into text accurately.
Finally there are what are sometimes called digital watermarks. These are created by embedding extra information, in the form of digital patterns, into images or sounds. The principle is to then scan the images or sounds and recognize the pattern, thus being able to ‘prove’ the ownership of the original. This is often used in the film and music industries to identify pirated copies. It is not very useful if you are protecting text because there is nowhere to ‘hide’ the watermark. LockLizard do not provide this kind of technique because the owner of the protected PDF document is clearly identified in it.
Download document security softwareDownload document security software that uses digital rights management controls to impose dynamic and static watermarks on your PDF documents.
Dynamically insert usernames, email address, date and time, yet only protect the document once for all users.
Document watermarks - watermarking documents for security. How dynamic and static watermarks can be applied to documents for security purposes and document control. LockLizard provides document security software that uses watermarks for document control. | |
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