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Copy-evident
Copy-evident documents have features that make it detectable that a copy is not the original. In security printing, various methods such as void pantograph are used to create patterns that are hard to copy exactly and when copied inexactly produces an easily detectable image. This can include halftone screens that are affected by the copying process, fine line patterns in different directions that are differently affected by copying and hence produce a mark, metallic inks causing diffraction or reflection. Copy-evident computer image files are also possible, for example by embedding a high-frequency pattern in a JPEG image that is imperceptible, but produces an obvious message when re-compressed with a different quality factor. Some forms of steganography, paper watermarking, and digital watermarking can be regarded as copy-evidence, although detecting that a document or file has been copied typically requires special inspection, tools or software. For example, 3D printed objec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Security Printing
Security printing is the field of the printing industry that deals with the printing of items such as banknotes, cheques, passports, tamper-evident labels, security tapes, product authentication, stock certificates, postage stamps and identity cards. The main goal of security printing is to prevent forgery, tampering, or counterfeiting. More recently many of the techniques used to protect these high-value documents have become more available to commercial printers, whether they are using the more traditional offset and flexographic presses or the newer digital platforms. Businesses are protecting their lesser-value documents such as transcripts, coupons and prescription pads by incorporating some of the features listed below to ensure that they cannot be forged or that alteration of the data cannot occur undetected. A number of technical methods are used in the security printing industry. Security printing is most often done on security paper, but it can also occur on plastic mate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Void Pantograph
In security printing, void pantograph refers to a method of making copy-evident and tamper-resistant patterns in the background of a document. Normally these are invisible to the eye, but become obvious when the document is photocopied. Typically they spell out "void", "copy", "invalid" or some other indicator message. Void pantographs work by exploiting the limitations and features of copying equipment. A scanner or photocopier will act as a low-pass filter on the original image, blurring edges slightly. It will also not be perfectly aligned with the directions of the document, causing aliasing. Features smaller than the resolution will also not be reproduced. In addition, human vision is sensitive to luminance contrast ratio The contrast ratio (CR) is a property of a display system, defined as the ratio of the luminance of the brightest shade (white) to that of the darkest shade (black) that the system is capable of producing. A high contrast ratio is a desired aspec .... This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halftone
Halftone is the reprographic Reprography (a portmanteau of ''reproduction'' and ''photography'') is the reproduction of graphics through mechanical or electrical means, such as photography or xerography. Reprography is commonly used in catalogs and archives, as well as in th ... technique that simulates continuous-tone imagery through the use of dots, varying either in size or in spacing, thus generating a gradient-like effect.Campbell, Alastair. The Designer's Lexicon. ©2000 Chronicle, San Francisco. "Halftone" can also be used to refer specifically to the image that is produced by this process. Where continuous-tone imagery contains an infinite range of colors or greys, the halftone process reduces visual reproductions to an image that is printed with only one color of ink, in dots of differing size (pulse-width modulation) or spacing (frequency modulation) or both. This reproduction relies on a basic optical illusion: when the halftone dots are small, the human eye inter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JPEG
JPEG ( ) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality. Since its introduction in 1992, JPEG has been the most widely used image compression standard in the world, and the most widely used digital image format, with several billion JPEG images produced every day as of 2015. The term "JPEG" is an acronym for the Joint Photographic Experts Group, which created the standard in 1992. JPEG was largely responsible for the proliferation of digital images and digital photos across the Internet, and later social media. JPEG compression is used in a number of image file formats. JPEG/Exif is the most common image format used by digital cameras and other photographic image capture devices; along with JPEG ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steganography
Steganography ( ) is the practice of representing information within another message or physical object, in such a manner that the presence of the information is not evident to human inspection. In computing/electronic contexts, a computer file, message, image, or video is concealed within another file, message, image, or video. The word ''steganography'' comes from Greek ''steganographia'', which combines the words ''steganós'' (), meaning "covered or concealed", and ''-graphia'' () meaning "writing". The first recorded use of the term was in 1499 by Johannes Trithemius in his '' Steganographia'', a treatise on cryptography and steganography, disguised as a book on magic. Generally, the hidden messages appear to be (or to be part of) something else: images, articles, shopping lists, or some other cover text. For example, the hidden message may be in invisible ink between the visible lines of a private letter. Some implementations of steganography that lack a shared secret are f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watermark
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. Watermarks have been used on postage stamps, currency, and other government documents to discourage counterfeiting. There are two main ways of producing watermarks in paper; the ''dandy roll process'', and the more complex ''cylinder mould process''. Watermarks vary greatly in their visibility; while some are obvious on casual inspection, others require some study to pick out. Various aids have been developed, such as ''watermark fluid'' that wets the paper without damaging it. A watermark is very useful in the examination of paper because it can be used for dating documents and artworks, identifying sizes, mill trademarks and locations, and determining the quality of a sheet of paper. The word is also used for digital ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Watermarking
A digital watermark is a kind of marker covertly embedded in a noise-tolerant signal such as audio, video or image data. It is typically used to identify ownership of the copyright of such signal. "Watermarking" is the process of hiding digital information in a carrier signal; the hidden information should,Ingemar J. Cox: ''Digital watermarking and steganography''. Morgan Kaufmann, Burlington, MA, USA, 2008 but does not need to, contain a relation to the carrier signal. Digital watermarks may be used to verify the authenticity or integrity of the carrier signal or to show the identity of its owners. It is prominently used for tracing copyright infringements and for banknote authentication. Like traditional physical watermarks, digital watermarks are often only perceptible under certain conditions, e.g. after using some algorithm.Frank Y. Shih: ''Digital watermarking and steganography: fundamentals and techniques''. Taylor & Francis, Boca Raton, FL, USA, 2008 If a digital watermark ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3D Printing
3D printing or additive manufacturing is the Manufacturing, construction of a three-dimensional object from a computer-aided design, CAD model or a digital 3D modeling, 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under Computer Numerical Control, computer control, with material being added together (such as plastics, liquids or powder grains being fused), typically layer by layer. In the 1980s, 3D printing techniques were considered suitable only for the production of functional or aesthetic prototypes, and a more appropriate term for it at the time was rapid prototyping. , the precision, repeatability, and material range of 3D printing have increased to the point that some 3D printing processes are considered viable as an industrial-production technology, whereby the term ''additive manufacturing'' can be used synonymously with ''3D printing''. One of the key advantages of 3D printing is the ability to produce very ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copy Detection Pattern
A copy detection pattern (CDP) or graphical code is a small Randomness, random or Pseudorandomness, pseudo-random digital image which is printed on documents, labels or products for counterfeit detection. Authentication is made by scanning the printed CDP using an image scanner or mobile phone camera. It is possible to store additional product-specific data into the CDP that will be decoded during the scanning process. A CDP can also be inserted into a 2D barcode to facilitate smartphone authentication and to connect with traceability data. Principle The detection of counterfeits using a CDP relies on an "information loss principle", which states that every time a digital image is printed or scanned, some information about the original digital image is lost. A CDP is a maximum entropy image that attempts to take advantage of this information loss. Since producing a counterfeit CDP requires an additional scanning and printing processes, it will have less information tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forgery
Forgery is a white-collar crime that generally refers to the false making or material alteration of a legal instrument with the specific intent to defraud anyone (other than themself). Tampering with a certain legal instrument may be forbidden by law in some jurisdictions but such an offense is not related to forgery unless the tampered legal instrument was actually used in the course of the crime to defraud another person or entity. Copies, studio replicas, and reproductions are not considered forgeries, though they may later become forgeries through knowing and willful misrepresentations. Forging money or currency is more often called counterfeiting. But consumer goods may also be ''counterfeits'' if they are not manufactured or produced by the designated manufacturer or producer given on the label or flagged by the trademark symbol. When the object forged is a record or document it is often called a false document. This usage of "forgery" does not derive from metalwork d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Authentication Methods
Authentication (from ''authentikos'', "real, genuine", from αὐθέντης ''authentes'', "author") is the act of proving an assertion, such as the identity of a computer system user. In contrast with identification, the act of indicating a person or thing's identity, authentication is the process of verifying that identity. It might involve validating personal identity documents, verifying the authenticity of a website with a digital certificate, determining the age of an artifact by carbon dating, or ensuring that a product or document is not counterfeit. Methods Authentication is relevant to multiple fields. In art, antiques, and anthropology, a common problem is verifying that a given artifact was produced by a certain person or in a certain place or period of history. In computer science, verifying a user's identity is often required to allow access to confidential data or systems. Authentication can be considered to be of three types: The first type of auth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
