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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 ...
A watermark is an identifying image or pattern in paper that appears as various shades of lightness/darkness when viewed by transmitted light (or when viewed by reflected light, atop a dark background), caused by thickness or density variations in the paper. [1]
Barack Obama's birth certificate on security paper.. Security paper is a paper used in security printing that incorporates features that can be used to identify or authenticate a document as original, e.g., watermarks or invisible fibres in paper, or features that demonstrate tamper evidence when fraud is attempted, e.g., to remove or alter print such as amounts or signatures on a cheque.
A watermark is made by impressing a water coated metal stamp or dandy roll onto the paper during manufacturing. Watermarks were first introduced in Bologna, Italy in 1282; as well as their use in security printing, they have also been used by paper makers to identify their product.
The first successful embedding and extraction of a steganographic spread spectrum watermark was demonstrated in 1993 by Andrew Tirkel, Gerard Rankin, Ron Van Schyndel, Charles Osborne, and others. [4] Watermarks are identification marks produced during the paper-making process.
Recycling codes on products. Recycling codes are used to identify the materials out of which the item is made, to facilitate easier recycling process.The presence on an item of a recycling code, a chasing arrows logo, or a resin code, is not an automatic indicator that a material is recyclable; it is an explanation of what the item is made of.
The paper, shortly after being drawn from the vat, is usually pressed with a Dandy roll as the mechanism to imprint a watermark onto the paper. Machine-made paper can produce single sheets of paper or one large continuous web of paper that is collected to form large rolls.
A number of authentication systems are known by the general term of "watermarking" methods, since they rely on embedding authentication information into another information bearer, by analogy with the watermarking of paper.