1.
AOL
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AOL Inc. is an American multinational mass media corporation based in New York, a subsidiary of Verizon Communications. AOL was one of the pioneers of the Internet in the mid-1990s. It originally provided a service to millions of Americans, as well as providing a web portal, e-mail, instant messaging. At the height of its popularity, it purchased the media conglomerate Time Warner in the largest merger in U. S. history, AOL rapidly declined thereafter, partly due to the decline of dial-up to broadband. AOL was eventually spun off from Time Warner in 2009, with Tim Armstrong appointed the new CEO, under his leadership, the company invested in media brands and advertising technologies. On June 23,2015, AOL was acquired by Verizon Communications for $4.4 billion, in the following months, AOL also made a deal with Microsoft and acquired several tech properties, including Millennial Media and Kanvas to bolster their mobile ad-tech capabilities. AOL began in 1983, as a venture called Control Video Corporation. Its sole product was a service called GameLine for the Atari 2600 video game console. Subscribers bought a modem from the company for US$49.95, GameLine permitted subscribers to temporarily download games and keep track of high scores, at a cost of US$1 per game. The telephone disconnected and the game would remain in GameLines Master Module and playable until the user turned off the console or downloaded another game. In January 1983, Steve Case was hired as a consultant for Control Video on the recommendation of his brother. In May 1983, Jim Kimsey became a consultant for Control Video. Kimsey was brought in by his West Point friend Frank Caufield, in early 1985, von Meister left the company. The technical team consisted of Marc Seriff, Tom Ralston, Ray Heinrich, Steve Trus, Ken Huntsman, Janet Hunter, Dave Brown, Craig Dykstra, Doug Coward, in 1987, Case was promoted again to executive vice-president. Kimsey soon began to groom Case to take over the role of CEO, Kimsey changed the companys strategy, and in 1985, launched a dedicated online service for Commodore 64 and 128 computers, originally called Quantum Link. The Quantum Link software was based on software licensed from PlayNet, the service was different from other online services as it used the computing power of the Commodore 64 and the Apple II rather than just a dumb terminal. It passed tokens back and forth and provided a fixed price service tailored for home users, in May 1988, Quantum and Apple launched AppleLink Personal Edition for Apple II and Macintosh computers. In August 1988, Quantum launched PC Link, a service for IBM-compatible PCs developed in a joint venture with the Tandy Corporation, after the company parted ways with Apple in October 1989, Quantum changed the services name to America Online
2.
Client (computing)
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A client is a piece of computer hardware or software that accesses a service made available by a server. The server is often on another system, in which case the client accesses the service by way of a network. The term applies to the role that programs or devices play in the client–server model, a client is a computer program that, as part of its operation, relies on sending a request to another computer program. For example, web browsers are clients that connect to web servers, email clients retrieve email from mail servers. Online chat uses a variety of clients, which depending on the chat protocol being used. Multiplayer video games or online video games may run as a client on each computer, the term client may also be applied to computers or devices that run the client software or users that use the client software. A client is part of a model, which is still used today. Clients and servers may be computer programs run on the same machine, combined with Internet sockets, programs may connect to a service operating on a possibly remote system through the Internet protocol suite. Servers wait for clients to initiate connections that they may accept. The term was first applied to devices that were not capable of running their own stand-alone programs and these dumb terminals were clients of the time-sharing mainframe computer. In one classification, client computers and devices are either fat clients, thin clients, or hybrid clients. A fat client, also known as a client or thick client, is a client that performs the bulk of any data processing operations itself. The personal computer is an example of a fat client, because of its relatively large set of features and capabilities. For example, a running a CAD program that ultimately shares the result of its work on a network is a fat client. A thin client is a sort of client. Thin clients use the resources of the host computer, a thin client generally only presents processed data provided by an application server, which performs the bulk of any required data processing. A device using web application is a thin client, a hybrid client is a mixture of the above two client models. Similar to a fat client, it processes locally, but relies on the server for storing persistent data and this approach offers features from both the fat client and the thin client
3.
Software
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Computer software, or simply software, is that part of a computer system that consists of data or computer instructions, in contrast to the physical hardware from which the system is built. In computer science and software engineering, computer software is all information processed by computer systems, programs, computer software includes computer programs, libraries and related non-executable data, such as online documentation or digital media. Computer hardware and software require each other and neither can be used on its own. At the lowest level, executable code consists of machine language instructions specific to an individual processor—typically a central processing unit, a machine language consists of groups of binary values signifying processor instructions that change the state of the computer from its preceding state. For example, an instruction may change the value stored in a storage location in the computer—an effect that is not directly observable to the user. An instruction may also cause something to appear on a display of the computer system—a state change which should be visible to the user. The processor carries out the instructions in the order they are provided, unless it is instructed to jump to a different instruction, the majority of software is written in high-level programming languages that are easier and more efficient for programmers, meaning closer to a natural language. High-level languages are translated into machine language using a compiler or an interpreter or a combination of the two, an outline for what would have been the first piece of software was written by Ada Lovelace in the 19th century, for the planned Analytical Engine. However, neither the Analytical Engine nor any software for it were ever created, the first theory about software—prior to creation of computers as we know them today—was proposed by Alan Turing in his 1935 essay Computable numbers with an application to the Entscheidungsproblem. This eventually led to the creation of the academic fields of computer science and software engineering. Computer science is more theoretical, whereas software engineering focuses on practical concerns. However, prior to 1946, software as we now understand it—programs stored in the memory of stored-program digital computers—did not yet exist, the first electronic computing devices were instead rewired in order to reprogram them. On virtually all platforms, software can be grouped into a few broad categories. There are many different types of software, because the range of tasks that can be performed with a modern computer is so large—see list of software. System software includes, Operating systems, which are collections of software that manage resources and provides common services for other software that runs on top of them. Supervisory programs, boot loaders, shells and window systems are parts of operating systems. In practice, an operating system bundled with additional software so that a user can potentially do some work with a computer that only has an operating system. Device drivers, which operate or control a particular type of device that is attached to a computer, utilities, which are computer programs designed to assist users in the maintenance and care of their computers
4.
Image
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Images may be two-dimensional, such as a photograph or screen display, or three-dimensional, such as a statue or hologram. They may be captured by optical devices – such as cameras, mirrors, lenses, telescopes, microscopes, etc. and natural objects and phenomena, such as the human eye or water. The word image is used in the broader sense of any two-dimensional figure such as a map, a graph. A volatile image is one that only for a short period of time. This may be a reflection of an object by a mirror, a fixed image, also called a hard copy, is one that has been recorded on a material object, such as paper or textile by photography or any other digital process. A mental image exists in a mind, as something one remembers or imagines. The subject of an image need not be real, it may be a concept, such as a graph, function. For example, Sigmund Freud claimed to have dreamed purely in aural-images of dialogs, a still image is a single static image, as distinguished from a kinetic image. This phrase is used in photography, visual media and the industry to emphasize that one is not talking about movies. A film still is a taken on the set of a movie or television program during production. In literature, imagery is a picture which appeals to the senses. It can both be figurative and literal, a moving image is typically a movie or video, including digital video. It could also be an animated display such as a zoetrope, library of Congress – Format Descriptions for Still Images Image Processing – Online Open Research Group Legal Issues Regarding Images Image Copyright Case
5.
Image compression
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Image compression is a type of data compression applied to digital images, to reduce their cost for storage or transmission. Algorithms may take advantage of visual perception and the properties of image data to provide superior results compared with generic compression methods. Image compression may be lossy or lossless, lossless compression is preferred for archival purposes and often for medical imaging, technical drawings, clip art, or comics. Lossy compression methods, especially used at low bit rates. Lossy methods are suitable for natural images such as photographs in applications where minor loss of fidelity is acceptable to achieve a substantial reduction in bit rate. Lossy compression that produces negligible differences may be called visually lossless, the selected colors are specified in the color palette in the header of the compressed image. Each pixel just references the index of a color in the color palette and this is the most commonly used method. In particular, a Fourier-related transform such as the Discrete Cosine Transform is widely used, N. Ahmed, T. Natarajan and K. R. Rao, Discrete Cosine Transform, IEEE Trans. The DCT is sometimes referred to as DCT-II in the context of a family of discrete cosine transforms, the more recently developed wavelet transform is also used extensively, followed by quantization and entropy coding. Other names for scalability are progressive coding or embedded bitstreams, despite its contrary nature, scalability also may be found in lossless codecs, usually in form of coarse-to-fine pixel scans. Scalability is especially useful for previewing images while downloading them or for providing quality access to e. g. databases. There are several types of scalability, Quality progressive or layer progressive, resolution progressive, First encode a lower image resolution, then encode the difference to higher resolutions. Component progressive, First encode grey, then color, certain parts of the image are encoded with higher quality than others. This may be combined with scalability, compressed data may contain information about the image which may be used to categorize, search, or browse images. Such information may include color and texture statistics, small preview images, Compression algorithms require different amounts of processing power to encode and decode. Some high compression algorithms require high processing power, the quality of a compression method often is measured by the Peak signal-to-noise ratio. Image compression from MIT OpenCourseWare Image Coding Fundamentals A study about image compression Data Compression Basics FAQ, from comp. compression IPRG Open group related to image processing research resources
6.
JPEG
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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 size and image quality. JPEG typically achieves 10,1 compression with little loss in image quality. JPEG compression is used in a number of file formats. These format variations are not distinguished, and are simply called JPEG. The term JPEG is an initialism/acronym for the Joint Photographic Experts Group, the MIME media type for JPEG is image/jpeg, except in older Internet Explorer versions, which provides a MIME type of image/pjpeg when uploading JPEG images. JPEG files usually have an extension of. jpg or. jpeg. JPEG/JFIF supports a maximum size of 65, 535×65,535 pixels. JPEG stands for Joint Photographic Experts Group, the name of the committee created the JPEG standard. The Joint stood for ISO TC97 WG8 and CCITT SGVIII, in 1987 ISO TC97 became ISO/IEC JTC1 and in 1992 CCITT became ITU-T. Currently on the JTC1 side JPEG is one of two sub-groups of ISO/IEC Joint Technical Committee 1, Subcommittee 29, Working Group 1 – titled as Coding of still pictures, on the ITU-T side ITU-T SG16 is the respective body. The original JPEG group was organized in 1986, issuing the first JPEG standard in 1992, which was approved in September 1992 as ITU-T Recommendation T.81 and in 1994 as ISO/IEC 10918-1. The JPEG standard specifies the codec, which defines how an image is compressed into a stream of bytes and decompressed back into an image, the Exif and JFIF standards define the commonly used file formats for interchange of JPEG-compressed images. JPEG standards are formally named as Information technology – Digital compression, ISO/IEC10918 consists of the following parts, Ecma International TR/98 specifies the JPEG File Interchange Format, the first edition was published in June 2009. The JPEG compression algorithm is at its best on photographs and paintings of scenes with smooth variations of tone. For web usage, where the amount of used for an image is important. JPEG/Exif is also the most common format saved by digital cameras, on the other hand, JPEG may not be as well suited for line drawings and other textual or iconic graphics, where the sharp contrasts between adjacent pixels can cause noticeable artifacts. Such images may be saved in a lossless graphics format such as TIFF, GIF, PNG
7.
Proxy server
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In computer networks, a proxy server is a server that acts as an intermediary for requests from clients seeking resources from other servers. Proxies were invented to add structure and encapsulation to distributed systems, today, most proxies are web proxies, facilitating access to content on the World Wide Web, providing anonymity and may be used to bypass IP address blocking. A proxy server may reside on the local computer, or at various points between the users computer and destination servers on the Internet. A proxy server that passes requests and responses unmodified is usually called a gateway or sometimes a tunneling proxy, a forward proxy is an Internet-facing proxy used to retrieve from a wide range of sources. A reverse proxy is usually an internal-facing proxy used as a front-end to control, a reverse proxy commonly also performs tasks such as load-balancing, authentication, decryption or caching. An open proxy is a proxy server that is accessible by any Internet user. Gordon Lyon estimates there are hundreds of thousands of open proxies on the Internet, an anonymous open proxy allows users to conceal their IP address while browsing the Web or using other Internet services. There are varying degrees of anonymity however, as well as a number of methods of tricking the client into revealing itself regardless of the proxy being used, a reverse proxy is a proxy server that appears to clients to be an ordinary server. Requests are forwarded to one or more proxy servers which handle the request, the response from the proxy server is returned as if it came directly from the original server, leaving the client no knowledge of the origin servers. Reverse proxies are installed in the neighborhood of one or more web servers, all traffic coming from the Internet and with a destination of one of the neighborhoods web servers goes through the proxy server. The use of reverse originates in its counterpart forward proxy since the reverse proxy sits closer to the web server and this problem can partly be overcome by using the SubjectAltName feature of X.509 certificates. Load balancing, the proxy can distribute the load to several web servers. In such a case, the proxy may need to rewrite the URLs in each web page. Serve/cache static content, A reverse proxy can offload the web servers by caching static content like pictures, compression, the proxy server can optimize and compress the content to speed up the load time. Spoon feeding, reduces resource usage caused by slow clients on the web servers by caching the content the web server sent and this especially benefits dynamically generated pages. Security, the server is an additional layer of defence and can protect against some OS. However, it does not provide any protection from attacks against the web application or service itself, a content-filtering web proxy server provides administrative control over the content that may be relayed in one or both directions through the proxy. It is commonly used in commercial and non-commercial organizations to ensure that Internet usage conforms to acceptable use policy
8.
Brand
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A brand is a name, term, design, symbol, or other feature that distinguishes one seller’s product from those of others. Brands are used in business, marketing, and advertising, however, the term has been extended to mean a strategic personality for a product or company, so that ‘brand’ now suggests the values and promises that a consumer may perceive and buy into. Branding is a set of marketing and communication methods that help to distinguish a company from competitors, the key components that form a brands toolbox include a brand’s identity, brand communication, brand awareness, brand loyalty, and various branding strategies. Brand equity is the totality of a brands worth and is validated by assessing the effectiveness of these branding components. To reach such an invaluable brand prestige requires a commitment to a way of doing business. A corporation who exhibits a strong brand culture is dedicated on producing intangible outputs such as customer satisfaction, reduced price sensitivity and customer loyalty. A brand is in essence a promise to its customers that they can expect long-term security, when a customer is familiar with a brand or favours it incomparably to its competitors, this is when a corporation has reached a high level of brand equity. Many companies are beginning to understand there is often little to differentiate between products in the 21st century. Branding remains the last bastion for differentiation, in accounting, a brand defined as an intangible asset is often the most valuable asset on a corporation’s balance sheet. The word ‘brand’ is often used as a referring to the company that is strongly identified with a brand. Marque or make are often used to denote a brand of motor vehicle, a concept brand is a brand that is associated with an abstract concept, like breast cancer awareness or environmentalism, rather than a specific product, service, or business. A commodity brand is a associated with a commodity. The word, brand, derives from Dutch brand meaning to burn and this product was developed at Dhosi Hill, an extinct volcano in northern India. Roman glassmakers branded their works, with Ennion being the most prominent, the Italians used brands in the form of watermarks on paper in the 13th century. Blind Stamps, hallmarks, and silver-makers marks are all types of brand, industrialization moved the production of many household items, such as soap, from local communities to centralized factories. When shipping their items, the factories would literally brand their logo or insignia on the barrels used, Bass & Company, the British brewery, claims their red-triangle brand as the worlds first trademark. Another example comes from Antiche Fornaci Giorgi in Italy, which has stamped or carved its bricks with the same proto-logo since 1731, cattle-branding has been used since Ancient Egypt. The term, maverick, originally meaning an un-branded calf, came from a Texas pioneer rancher, Sam Maverick, use of the word maverick spread among cowboys and came to apply to unbranded calves found wandering alone
9.
Plug-in (computing)
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In computing, a plug-in is a software component that adds a specific feature to an existing computer program. When a program supports plug-ins, it enables customization, the common examples are the plug-ins used in web browsers to add new features such as search-engines, virus scanners, or the ability to use a new file type such as a new video format. Applications support plug-ins for many reasons, types of applications and why they use plug-ins, Audio editors use plug-ins to generate, process or analyse sound. Ardour and Audacity are examples of such editors, email clients use plug-ins to decrypt and encrypt email. Pretty Good Privacy is an example of such plug-ins, graphics software use plug-ins to support file formats and process images. Media players use plug-ins to support file formats and apply filters, foobar2000, GStreamer, Quintessential, VST, Winamp, XMMS are examples of such media players. Packet sniffers use plug-ins to decode packet formats, omniPeek is an example of such packet sniffers. Remote sensing applications use plug-ins to process data from different sensor types, Visual Studio itself can be plugged into other applications via Visual Studio Tools for Office and Visual Studio Tools for Applications. Web browsers use browser extensions to expand their functionality, examples include Adobe Flash Player, Java SE, QuickTime, Microsoft Silverlight and Unity. The host application provides services which the plug-in can use, including a way for plug-ins to register themselves with the host application, plug-ins depend on the services provided by the host application and do not usually work by themselves. Programmers typically implement plug-in functionality using shared libraries installed in a place prescribed by the host application, HyperCard supported a similar facility, but more commonly included the plug-in code in the HyperCard documents themselves. Thus the HyperCard stack became a self-contained application in its own right, programs may also implement plugins by loading a directory of simple script files written in a scripting language like Python or Lua. In Mozilla Foundation definitions, the words add-on, extension and plug-in are not synonyms, add-on can refer to anything that extends the functions of a Mozilla application. Extensions comprise a subtype, albeit the most common and the most powerful one, Mozilla applications come with integrated add-on managers that, similar to package managers, install, update and manage extensions. The term, Plug-in, however, strictly refers to NPAPI-based web content renderers, the plug-in program could make calls to the editor to have it perform text-editing services upon the buffer that the editor shared with the plug-in. The Waterloo Fortran compiler used this feature to allow interactive compilation of Fortran programs edited by EDT, very early PC software applications to incorporate plug-in functionality included HyperCard and QuarkXPress on the Macintosh, both released in 1987. In 1988, Silicon Beach Software included plug-in functionality in Digital Darkroom and SuperPaint, and Ed Bomke coined the term plug-in
10.
Windows 2000
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Windows 2000 is an operating system for use on both client and server computers. It was produced by Microsoft and released to manufacturing on December 15,1999 and it is the successor to Windows NT4.0, and is the last version of Microsoft Windows to display the Windows NT designation. It is succeeded by Windows XP and Windows Server 2003, during development, Windows 2000 was known as Windows NT5.0. Four editions of Windows 2000 were released, Professional, Server, Advanced Server, and Datacenter Server, Windows 2000 introduces NTFS3.0, Encrypting File System, as well as basic and dynamic disk storage. Support for people with disabilities was improved over Windows NT4.0 with a number of new assistive technologies, the Windows 2000 Server family has additional features including the ability to provide Active Directory services. Windows 2000 can be installed either a manual or unattended installation. Microsoft marketed Windows 2000 as the most secure Windows version ever at the time, however, it became the target of a number of high-profile virus attacks such as Code Red and Nimda. For ten years after its release, it continued to receive patches for security vulnerabilities nearly every month until reaching the end of its lifecycle on July 13,2010. Windows 2000 is a continuation of the Microsoft Windows NT family of operating systems, the original name for the operating system was Windows NT5.0 and its Beta 1 was released in September 1997, followed by Beta 2 in August 1998. On October 27,1998, Microsoft announced that the name of the version of the operating system would be Windows 2000. Windows 2000 Beta 3 was released in January 1999, NT5.0 Beta 1 was similar to NT4.0, including a very similar themed logo. NT5.0 Beta 2 introduced a new boot screen. The new login prompt from the version made its first appearance in Beta 3 build 1946. The new, updated icons first appeared in Beta 3 build 1976, the Windows 2000 boot screen in the final version first appeared in Beta 3 build 1994. Windows 2000 did not have a codename because, according to Dave Thompson of Windows NT team, Windows 2000 Service Pack 1 was codenamed Asteroid and Windows 2000 64-bit was codenamed Janus. During development, there was a build for the Alpha which was abandoned some time after RC1 after Compaq announced they had dropped support for Windows NT on Alpha. From here, Microsoft issued three release candidates between July and November 1999, and finally released the system to partners on December 12,1999. The public could buy the version of Windows 2000 on February 17,2000
11.
Microsoft
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Its best known software products are the Microsoft Windows line of operating systems, Microsoft Office office suite, and Internet Explorer and Edge web browsers. Its flagship hardware products are the Xbox video game consoles and the Microsoft Surface tablet lineup, as of 2016, it was the worlds largest software maker by revenue, and one of the worlds most valuable companies. Microsoft was founded by Paul Allen and Bill Gates on April 4,1975, to develop and it rose to dominate the personal computer operating system market with MS-DOS in the mid-1980s, followed by Microsoft Windows. The companys 1986 initial public offering, and subsequent rise in its share price, since the 1990s, it has increasingly diversified from the operating system market and has made a number of corporate acquisitions. In May 2011, Microsoft acquired Skype Technologies for $8.5 billion, in June 2012, Microsoft entered the personal computer production market for the first time, with the launch of the Microsoft Surface, a line of tablet computers. The word Microsoft is a portmanteau of microcomputer and software, Paul Allen and Bill Gates, childhood friends with a passion for computer programming, sought to make a successful business utilizing their shared skills. In 1972 they founded their first company, named Traf-O-Data, which offered a computer that tracked and analyzed automobile traffic data. Allen went on to pursue a degree in science at Washington State University. The January 1975 issue of Popular Electronics featured Micro Instrumentation and Telemetry Systemss Altair 8800 microcomputer, Allen suggested that they could program a BASIC interpreter for the device, after a call from Gates claiming to have a working interpreter, MITS requested a demonstration. Since they didnt actually have one, Allen worked on a simulator for the Altair while Gates developed the interpreter and they officially established Microsoft on April 4,1975, with Gates as the CEO. Allen came up with the name of Micro-Soft, as recounted in a 1995 Fortune magazine article. In August 1977 the company formed an agreement with ASCII Magazine in Japan, resulting in its first international office, the company moved to a new home in Bellevue, Washington in January 1979. Microsoft entered the OS business in 1980 with its own version of Unix, however, it was MS-DOS that solidified the companys dominance. For this deal, Microsoft purchased a CP/M clone called 86-DOS from Seattle Computer Products, branding it as MS-DOS, following the release of the IBM PC in August 1981, Microsoft retained ownership of MS-DOS. Since IBM copyrighted the IBM PC BIOS, other companies had to engineer it in order for non-IBM hardware to run as IBM PC compatibles. Due to various factors, such as MS-DOSs available software selection, the company expanded into new markets with the release of the Microsoft Mouse in 1983, as well as with a publishing division named Microsoft Press. Paul Allen resigned from Microsoft in 1983 after developing Hodgkins disease, while jointly developing a new OS with IBM in 1984, OS/2, Microsoft released Microsoft Windows, a graphical extension for MS-DOS, on November 20,1985. Once Microsoft informed IBM of NT, the OS/2 partnership deteriorated, in 1990, Microsoft introduced its office suite, Microsoft Office
12.
Internet Explorer
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Internet Explorer is a discontinued series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems, starting in 1995. It was first released as part of the add-on package Plus. for Windows 95 that year, later versions were available as free downloads, or in service packs, and included in the original equipment manufacturer service releases of Windows 95 and later versions of Windows. Internet Explorer was one of the most widely used web browsers and this came after Microsoft used bundling to win the first browser war against Netscape, which was the dominant browser in the 1990s. Estimates for Internet Explorers overall market share range from 5. 45% to 27. 38% or by StatCounters numbers ranked 3rd, just after Firefox, as of August 2016. Microsoft spent over US$100 million per year on Internet Explorer in the late 1990s, on March 17,2015, Microsoft announced that Microsoft Edge would replace Internet Explorer as the default browser on its Windows 10 devices. This effectively makes Internet Explorer 11 the last release, Internet Explorer will, however, remain on some versions of Windows 10 primarily for enterprise purposes. Starting January 12,2016, only Internet Explorer 11 is supported with more security than older versions, support varies based on the operating systems technical capabilities and its support lifecycle. The Internet Explorer project was started in the summer of 1994 by Thomas Reardon, Mosaic, which was an early commercial web browser with formal ties to the pioneering National Center for Supercomputing Applications Mosaic browser. In late 1994, Microsoft licensed Spyglass Mosaic for a fee plus a percentage of Microsofts non-Windows revenues for the software. Although bearing a similar to NCSA Mosaic, Spyglass Mosaic had used the NCSA Mosaic source code sparingly. Microsoft was sued by Synet Inc. in 1996, over the trademark infringement, the first version of Internet Explorer, Microsoft Internet Explorer made its debut on August 16,1995. It was a version of Spyglass Mosaic, which Microsoft licensed from Spyglass Inc. like many other companies initiating browser development. It was installed as part of the Internet Jumpstart Kit in Microsoft Plus. for Windows 95, the Internet Explorer team began with about six people in early development. Internet Explorer 1.5 was released months later for Windows NT. By including it free of charge on their system, they did not have to pay royalties to Spyglass Inc, resulting in a lawsuit. Windows Internet Explorer 9 was released on March 14,2011, development for Internet Explorer 9 began shortly after the release of Internet Explorer 8. At MIX10, Microsoft showed and publicly released the first Platform Preview for Internet Explorer 9, ultimately, eight platform previews were released. The first public beta was released at an event in San Francisco
13.
International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
14.
Internet Archive
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The Internet Archive is a San Francisco–based nonprofit digital library with the stated mission of universal access to all knowledge. As of October 2016, its collection topped 15 petabytes, in addition to its archiving function, the Archive is an activist organization, advocating for a free and open Internet. Its web archive, the Wayback Machine, contains over 150 billion web captures, the Archive also oversees one of the worlds largest book digitization projects. Founded by Brewster Kahle in May 1996, the Archive is a 501 nonprofit operating in the United States. It has a budget of $10 million, derived from a variety of sources, revenue from its Web crawling services, various partnerships, grants, donations. Its headquarters are in San Francisco, California, where about 30 of its 200 employees work, Most of its staff work in its book-scanning centers. The Archive has data centers in three Californian cities, San Francisco, Redwood City, and Richmond, the Archive is a member of the International Internet Preservation Consortium and was officially designated as a library by the State of California in 2007. Brewster Kahle founded the Archive in 1996 at around the time that he began the for-profit web crawling company Alexa Internet. In October 1996, the Internet Archive had begun to archive and preserve the World Wide Web in large quantities, the archived content wasnt available to the general public until 2001, when it developed the Wayback Machine. In late 1999, the Archive expanded its collections beyond the Web archive, Now the Internet Archive includes texts, audio, moving images, and software. It hosts a number of projects, the NASA Images Archive, the contract crawling service Archive-It. According to its web site, Most societies place importance on preserving artifacts of their culture, without such artifacts, civilization has no memory and no mechanism to learn from its successes and failures. Our culture now produces more and more artifacts in digital form, the Archives mission is to help preserve those artifacts and create an Internet library for researchers, historians, and scholars. In August 2012, the Archive announced that it has added BitTorrent to its file download options for over 1.3 million existing files, on November 6,2013, the Internet Archives headquarters in San Franciscos Richmond District caught fire, destroying equipment and damaging some nearby apartments. The nonprofit Archive sought donations to cover the estimated $600,000 in damage, in November 2016, Kahle announced that the Internet Archive was building the Internet Archive of Canada, a copy of the archive to be based somewhere in the country of Canada. The announcement received widespread coverage due to the implication that the decision to build an archive in a foreign country was because of the upcoming presidency of Donald Trump. Kahle was quoted as saying that on November 9th in America and it was a firm reminder that institutions like ours, built for the long-term, need to design for change. For us, it means keeping our cultural materials safe, private and it means preparing for a Web that may face greater restrictions
15.
Raster graphics
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Raster images are stored in image files with varying formats. A raster is technically characterized by the width and height of the image in pixels, the printing and prepress industries know raster graphics as contones. The opposite to contones is line work, usually implemented as vector graphics in digital systems, the word raster has its origins in the Latin rastrum, which is derived from radere. It originates from the scan of cathode ray tube video monitors. By association, it can refer to a rectangular grid of pixels. The word rastrum is now used to refer to a device for drawing musical staff lines, most modern computers have bitmapped displays, where each on-screen pixel directly corresponds to a small number of bits in memory. The screen is refreshed simply by scanning through pixels and coloring them according to set of bits. The refresh procedure, being speed critical, is implemented by dedicated circuitry. Most computer images are stored in raster graphics formats or compressed variations, including GIF, JPEG, and PNG, three-dimensional voxel raster graphics are employed in video games and are also used in medical imaging such as MRI scanners. GIS programs commonly use rasters that encode geographic data in the values as well as the pixel locations. Raster graphics are resolution dependent, meaning they cannot scale up to a resolution without loss of apparent quality. This property contrasts with the capabilities of graphics, which easily scale up to the quality of the device rendering them. Raster graphics deal more practically than vector graphics with photographs and photo-realistic images, typically, a resolution of 150 to 300 PPI works well for 4-color process printing. However, for printing technologies that perform color mixing through dithering rather than through overprinting, printer DPI and image PPI have a different meaning. Thus, for instance, printing an image at 250 PPI may actually require a printer setting of 1200 DPI, when an image is rendered in a raster-based image editor, the image is composed of millions of pixels. At its core, an image editor works by manipulating each individual pixel. Most pixel-based image editors work using the RGB color model, and this article is based on material taken from the Free On-line Dictionary of Computing prior to 1 November 2008 and incorporated under the relicensing terms of the GFDL, version 1.3 or later
16.
APNG
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The Animated Portable Network Graphics file format is an extension to the Portable Network Graphics specification. It allows for animated PNG files that work similarly to animated GIF files, while supporting 24-bit images and it also retains backward compatibility with non-animated PNG files. The first frame of an APNG file is stored as a normal PNG stream, the frame speed data and extra animation frames are stored in extra chunks. APNG competes with Multiple-image Network Graphics, a format for bitmapped animations created by the same team as PNG. APNGs advantage is the library size and compatibility with older PNG implementations. The APNG specification was created in 2004 by Stuart Parmenter and Vladimir Vukićević of the Mozilla Corporation to allow for storing the animations needed for such as throbbers. Among users and maintainers of the PNG and MNG formats, APNG had a lukewarm reception, in particular, PNG was conceived to be a single-image format. The PNG group officially rejected APNG as an extension on April 20,2007. There have been several subsequent proposals for a simple animated graphics format based on PNG using several different approaches, Mozilla Firefox added support for APNG in version 3 trunk builds on March 23,2007. Iceweasel 3 supports APNG by using Mozillas unofficial variant of libpng, in 2008 WorldDMB adopted APNG as a backward compatible extension to enable animation as part of the MOT SlideShow user application for Digital Radio. APNG1.0 Specification - Animated Portable Network Graphics is included as normative Annex A in the ETSI standard TS101499 V2.2.1, in 2010 Commercial Radio Broadcasters in Sydney began to include APNG animations in DAB+ digital radio broadcasts. These APNG animations are carried by the MOT slideshow application which accompanies the audio services and it is expected that other cities in Australia will follow in early 2011. Mozillas role in extending the PNG format to APNG echoes Netscapes much earlier role in popularizing animated GIFs, in 2016, Apple adopted the APNG format as the preferred format for animated stickers in iOS10 iMessage apps. On March 15,2017 APNG support was added to Chromium and this leaves Microsoft Edges Rendering Engine as the only engine to not support the format. A server-side library exists that allows web browsers that support the canvas tag, examples of such browsers include Microsoft Edge and Internet Explorer 9. For image processing software that doesnt export to APNG, users can use a program called APNG Assembler and it creates highly optimized Animated PNG files from PNG/TGA image sequences. A PNG file consists of the PNG Signature, followed by a series of chunks, a chunk consists of four parts, Length, Chunk type, Chunk data and CRC. There are about 20 different chunk types, but for a minimal PNG, only 3 are required, The IHDR chunk, one or more IDAT chunks, the next graphic shows the contents of such a minimal PNG file, representing just one red pixel
17.
BMP file format
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The BMP file format is capable of storing two-dimensional digital images both monochrome and color, in various color depths, and optionally with data compression, alpha channels, and color profiles. The Windows Metafile specification covers the BMP file format, among others wingdi. h defines BMP constants and structures. They called these device-independent bitmaps or DIBs, and the format for them is called DIB file format or BMP image file format. According to Microsoft support, A device-independent bitmap is a used to define device-independent bitmaps in various color resolutions. The main purpose of DIBs is to allow bitmaps to be moved from one device to another, a DIB is an external format, in contrast to a device-dependent bitmap, which appears in the system as a bitmap object. A DIB is normally transported in metafiles, BMP files, the following sections discuss the data stored in the BMP file or DIB in detail. This is the standard BMP file format, some applications create bitmap image files which are not compliant with the Microsoft documentation. Also, not all fields are used, a value of 0 will be found in these unused fields, the bitmap image file consists of fixed-size structures as well as variable-size structures appearing in a predetermined sequence. Many different versions of some of these structures can appear in the file, the in-memory DIB data structure is almost the same as the BMP file format, but it does not contain the 14-byte bitmap file header and begins with the DIB header. For DIBs loaded in memory, the table can also consist of 16-bit entries that constitute indexes to the currently realized palette. In all cases, the array must begin at a memory address that is a multiple of 4 bytes. In non-packed DIBs loaded in memory, the optional color profile data should be located immediately after the table and before the gap1. In all cases, the array must begin at a memory address that is a multiple of 4 bytes. In some cases it may be necessary to adjust the number of entries in the table in order to force the memory address of the pixel array to a multiple of 4 bytes. For packed DIBs loaded in memory, the optional color profile data should immediately follow the pixel array, packed DIBs are required by Windows clipboard API functions as well as by some Windows patterned brush and resource functions. This block of bytes is at the start of the file and is used to identify the file, a typical application reads this block first to ensure that the file is actually a BMP file and that it is not damaged. The first 2 bytes of the BMP file format are the character B then the character M in ASCII encoding, all of the integer values are stored in little-endian format. This block of bytes tells the detailed information about the image
18.
BSAVE (bitmap format)
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A BSAVE Image as it is referenced in a graphics program is an image file format created usually by saving raw video memory to disk. The BASIC BSAVE command is a general command meant for dumping ranges of addresses to disk. Data could be recalled using the counterpart BLOAD command, some platforms provided a BRUN command that would immediately attempt to execute the loaded RAM image as a program. BSAVE was in use as a file format when the IBM PC was introduced. It was also in use on the Apple II in the same time period. Although the commands were available on the Commodore PET line, they were removed from the later Commodore 64, in 1985 the Commodore 128 was released with Commodore BASIC version 7.0 which restored the BSAVE and BLOAD commands. The BSAVED format is a device-dependent raster image format, the file header stores information about the hardware address. The graphics data follows the header directly and is stored as raw data in the format of the native adapters addressable memory, there is no file compression, and therefore these load very quickly and without much programming when displayed in native mode. No additional information, such as screen resolution, color depth and palette information, bit planes, Video adapters were simple when this format was in wide use and the other information necessary to display the image could usually be inferred by programs that loaded such files. The BASIC programming language was shipped as part of the system on the first IBM PCs, Apple. On computers that did not start up in BASIC, BASIC was loaded by manually running the BASIC interpreter, the user could then type BASIC commands in direct mode or by creating and/or running a numbered BASIC program within the interpreter. One of the commands that early BASIC offered was BSAVE and another command was BLOAD, using the BSAVE command, an addressable area and length of memory could be saved to disk as a named file. This Image of saved memory could then be reloaded from disk into addressable memory later with the BLOAD command, if the BSAVEd image contained program code it could be executed, if data it could be used again, and if the BSAVEd image contained graphics it could be viewed. The video area of memory was addressable, the PUT and GET commands were used in addition to the BSAVE and BLOAD commands on the IBM PC to allow clips of the screen to be pre-formatted for BSAVE and BLOAD. PUT and GET allowed display modifier verbs which resembled functions in the Windows Graphical Device Interface used by programmers later. Microsoft produced the BASIC interpreters that were bundled with the IBM PC, Apple II, and Commodore PET, and included the ability to BSAVE and BLOAD RAM images on all 3 platforms. It was possible for users of the day to use the BLOAD command to load a graphics image that had been BSAVED in addition to loading a BSAVED executable or data image. With the passing of MS-DOS so did the use of DOS programs that saved in the BSAVED format and their use by programmers has stopped because the BLOAD command is no longer supported in modern programming languages which discourage accessing video memory directly
19.
FITS
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Flexible Image Transport System is an open standard defining a digital file format useful for storage, transmission and processing of scientific and other images. FITS is the most commonly used digital file format in astronomy, the FITS format was first standardized in 1981, it has evolved gradually since then, and the most recent version was standardized in 2008. FITS was designed with an eye towards long-term archival storage, a major feature of the FITS format is that image metadata is stored in a human-readable ASCII header, so that an interested user can examine the headers to investigate a file of unknown provenance. The information in the header is designed to calculate the byte offset of some information in the subsequent data unit to direct access to the data cells. Each FITS file consists of one or more headers containing ASCII card images that carry keyword/value pairs, FITS is also often used to store non-image data, such as spectra, photon lists, data cubes, or even structured data such as multi-table databases. A FITS file may contain several extensions, and each of these may contain a data object, for example, it is possible to store x-ray and infrared exposures in the same file. The earliest and still most commonly used type of FITS data is an image header/data block, the term image is somewhat loosely applied, as the format supports data arrays of arbitrary dimension—normal image data are usually 2-D or 3-D. The data themselves may be in one of several integer and floating-point formats, FITS image headers can contain information about one or more scientific coordinate systems that are overlaid on the image itself. The WCS standard includes many different spherical projections, including, for example, FITS also supports tabular data with named columns and multidimensional rows. Both binary and ASCII table formats have been specified, the data in each column of the table can be in a different format from the others. Together with the ability to string multiple header/data blocks together, this allows FITS files to represent entire relational databases, the FITS Support Office at NASA/GSFC maintains a list of libraries and platforms that currently support FITS. Image processing programs such as ImageJ, GIMP, Photoshop, XnView and IrfanView can generally read simple FITS images, scientific teams frequently write their own code to interact with their FITS data, using the tools available in their language of choice. The FITS Liberator software is used by imaging scientists at the European Space Agency, the SAOImage DS9 Astronomical Data Visualization Application is available for many OSs, and handles images and headers. Many scientific computing environments make use of the system data in the FITS header to display, compare, rectify. The FITS standard version 3.0 was officially approved by the IAU FITS Working Group in July 2008, FITS I/O Libraries, a list of software for reading and writing FITS files for various languages
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GIF
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The format supports up to 8 bits per pixel for each image, allowing a single image to reference its own palette of up to 256 different colors chosen from the 24-bit RGB color space. It also supports animations and allows a separate palette of up to 256 colors for each frame, GIF images are compressed using the Lempel–Ziv–Welch lossless data compression technique to reduce the file size without degrading the visual quality. This compression technique was patented in 1985, controversy over the licensing agreement between the software patent holder, Unisys, and CompuServe in 1994 spurred the development of the Portable Network Graphics standard. By 2004 all the relevant patents had expired, CompuServe introduced the GIF format in 1987 to provide a color image format for their file downloading areas, replacing their earlier run-length encoding format, which was black and white only. The original version of the GIF format was called 87a, in 1989, CompuServe released an enhanced version, called 89a, which added support for animation delays, transparent background colors, and storage of application-specific metadata. The 89a specification also supports incorporating text labels as text, but as there is control over display fonts. The two versions can be distinguished by looking at the first six bytes of the file, which, CompuServe encouraged the adoption of GIF by providing downloadable conversion utilities for many computers. By December 1987, for example, an Apple IIGS user could view pictures created on an Atari ST or Commodore 64, GIF was one of the first two image formats commonly used on Web sites, the other being the black-and-white XBM. In September 1995 Netscape Navigator 2.0 added Animated GIF support, the feature of storing multiple images in one file, accompanied by control data, is used extensively on the Web to produce simple animations. As a noun, the word GIF is found in the editions of many dictionaries. In 2012, the American wing of the Oxford University Press recognized GIF as a verb as well, meaning to create a GIF file, as in GIFing was perfect medium for sharing scenes from the Summer Olympics. The presss lexicographers voted it their word of the year, saying that GIFs have evolved into a tool with serious applications including research, in May 2015 Facebook added GIF support, even though they originally didnt support them on their site. The creators of the format pronounced the word as jif with a soft G /ˈdʒɪf/ as in gin, the word is now also widely pronounced with a hard G /ˈɡɪf/ as in gift. The American Heritage Dictionary cites both, indicating jif as the pronunciation, while Cambridge Dictionary of American English offers only the hard-G pronunciation. Merriam-Websters Collegiate Dictionary and the OED cite both pronunciations, but place gif in the default position, the New Oxford American Dictionary gave only jif in its 2nd edition but updated it to jif, gif in its 3rd edition. The disagreement over the pronunciation led to heated Internet debate, the White House and TV program Jeopardy. Also waded into the debate during 2013, GIFs are suitable for sharp-edged line art with a limited number of colors. This takes advantage of the formats lossless compression, which favors flat areas of color with well defined edges
21.
SilverFast
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SilverFast is the name of a family of software for image scanning and processing, including photos, documents and slides, developed by LaserSoft Imaging. SilverFast was introduced in 1995, Version 3.0 was finished in December 1996 and it is the only software supporting the Heidelberg scanner on Mac OS X and Microsoft Windows 2000, XP, Vista and 7. Some scanner manufacturers bundle their hardware with SilverFast, in 2011 version 8 was introduced, and HDR imaging software followed in 2012. Optional, 1)Multi-Exposure, 2)ICC Printer Calibration, 3)PhotoProof, 4)ColorServer It can be used as an application, as a Photoshop plug-in. It contains features for reading the data from the camera, for processing, optimizing. SilverFast DC Pro has the functionality of the scanner-software SilverFast Ai for digital images, supported are the standard image formats such as JPEG and TIFF, and unprocessed raw image format. The access to the raw data permits manual color correction or sharpening instead of using the automatic adjustment. SilverFast DC supports Adobe DNG and many models, some optimized by special camera profiles. With the included IT8-target, individual ICC profiles can be self-made for every camera, SilverFast DC Pro also has automated color optimization AACO, support for JPEG2000, unsharpmasking USMPlus, CloneTool, and an improved PrinTao module with text and layout functions. SilverFast HDR is a program for processing 48-bit raw images. Many newer scanners are able to output the image directly with all existing data instead of breaking it down to 24-bit and this 48-bit raw image can be saved immediately and digital processing performed later. SilverFast HDR can be used as a native plug-in for Adobe Photoshop, as a universal TWAIN module, the HDR Studio has AACO, JPEG2000, USMPlus, CloneTool and PrinTao. With version 6.6.1 any SilverFast HDR version supports the proprietary RAW data format HDRi and these 64-bit HDRi color files and 32-bit HDRi greyscale files contain additional 16-bit infrared RAW data besides the 48-bit color RAW data and 16-bit greyscale RAW data respectively. Therefore, a scanner with a channel available to the software is necessary. This RAW format can keep any readable image information for later post-processing, the acronym HDR as used by SilverFast is not related to High-dynamic-range imaging, a widely used technique to increase the dynamic range of images. The data format is, The SilverFast Archive Suite includes SilverFast Ai IT8 and this package is suitable for archiving slides, negatives, and photos, whereas the post processing can take place anytime after scanning. Templates can be used to make workflow easier and faster by reducing similar, PrinTao has predefined templates to which the user can add self-made ones. The PrinTao module is already included in the SilverFast Ai / DC / HDR Studio versions and this is accomplished by scanning the original multiple times with different exposure times, increasing the dynamic range and preserving detail in the light and shadow areas of the image
22.
Apple Icon Image format
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The Apple Icon Image format is the icon format used in Apple Inc. s macOS. It supports icons of 16 ×16,32 ×32,48 ×48,128 ×128,256 ×256,512 ×512, the fixed-size icons can be scaled by the operating system and displayed at any intermediate size. The file format consists of an 8 byte header, followed by any number of icons, over time the format has been improved and there is support for compression of some parts of the pixel data. The 32-bit pixel data is compressed with a format similar to PackBits. Some sources mentioned that the OS supports both compressed or uncompressed data chunks, the values inside the brackets in the length column is the uncompressed length. Various image viewers can load *. icns files, a free, gTK+ can load *. icns resources since 2007. Other tools supporting the format include the Apple Icon Composer and icns Browser, The Iconfactory, ICO format on Windows X PixMap format for X11
23.
ILBM
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The LBM file extension is an image file in Interchange File Format structure to store image or palette data. Most commonly you can find these files in InterLeaved BitMap format, but some games are using a similar, both formats commonly exist under the. lbm file extension, occasionally appearing also as. bbm extension. ILBM and PBM formats are used by games from late 80s, in essence LBM files consist of a number of consecutive chunks, whose order can, to some extent, be varied. Each chunk has a different function and has the basic format. This means that a program does not have to read or decode every chunk in a file, for example, a program might use a TIME chunk to store the date and time that a file was last edited. For details on the structure and how to read them. LBM files usually contain enough information to them to be displayed by an image editing program, including image dimensions, palette. Some files were designed to act as palettes for paint programs or to be merged into another image and this makes them much more flexible, but also much more complex than other formats such as BMP. For LBMs the BMHD chunk and any other vital chunks must appear before the BODY chunk, any chunks appearing after BODY are considered extra and many programs will leave them unread and unchanged. There are many possible chunk types, however, there are only a limited number of common chunk types used and understood by most programs, and descriptions of these follow. Again refer to Interchange File Format for further detail about finding and handling chunks, the BMHD chunk specifies how the image is to be displayed and is usually the first chunk inside the FORM. It not only defines the images height/width, but where it is drawn on the screen, how to display it in various screen resolutions, the content of this chunk is as follows, The BODY chunk is usually the last chunk in a file, and the largest. In ILBM files the BODY chunk stores the image data as interleaved bitplanes by row. The bitplanes appear first from 1 to n, followed by the mask plane, in PBM files the BODY chunk is simpler as uncompressed it is just a continuous stream of bytes containing image data. If an image is compressed, each row of data is compressed individually, the compression is a variety of RLE Compression using flags. It can be decoded as follows, Loop until we have bytes worth of data While <, Read a byte If >128, then, Read the next byte, Move forward 2 bytes and return to step 1. Else if <128, then, Read and output the next bytes Move forward bytes, always encode >3 byte repeats as replicate runs. A CAMG chunk is specifically for the Commodore Amiga computer and it stores a LONG viewport mode
24.
JBIG2
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JBIG2 is an image compression standard for bi-level images, developed by the Joint Bi-level Image Experts Group. It is suitable for both lossless and lossy compression, JBIG2 has been published in 2000 as the international standard ITU T.88, and in 2001 as ISO/IEC14492. Ideally, a JBIG2 encoder will segment the input page into regions of text, regions of halftone images, regions that are neither text nor halftones are typically compressed using a context-dependent arithmetic coding algorithm called the MQ coder. Textual regions are compressed as follows, the pixels in the regions are grouped into symbols. A dictionary of symbols is then created and encoded, typically also using context-dependent arithmetic coding, typically, a symbol will correspond to a character of text, but this is not required by the compression method. Halftone images may be compressed by reconstructing the image used to generate the halftone. Overall, the used by JBIG2 to compress text is very similar to the JB2 compression scheme used in the DjVu file format for coding binary images. PDF files versions 1.4 and above may contain JBIG2-compressed data, open-source decoders for JBIG2 are jbig2dec, the java-based jbig2-imageio and the decoder found in versions 2.00 and above of xpdf. Typically, an image consists mainly of a large amount of textual and halftone data. The bi-level image is segmented into three regions, text, halftone, and generic regions, each region is coded differently and the coding methodologies are described in the following passage. Text coding is based on the nature of human visual interpretation, a human observer cannot tell the difference between two instances of the same characters in a bi-level image even though they may not exactly match pixel by pixel. Therefore, only the bitmap of one representative character instance needs to be coded instead of coding the bitmaps of each occurrence of the same character individually, for each character instance, the coded instance of the character is then stored into a symbol dictionary. There are two encoding methods for image data, pattern matching and substitution and soft pattern matching. These methods are presented in the following subsections, the position is usually relative to another previously coded character. If a match is not found, the segmented pixel block is coded directly, typical procedures of pattern matching and substitution algorithm are displayed in the left block diagram of the figure above. Although the method of PM&S can achieve outstanding compression, substitution errors could be made during the process if the resolution is low. The deployment of refinement data can make the character-substitution error mentioned earlier highly unlikely, the refinement data contains the current desired character instance, which is coded using the pixels of both the current character and the matching character in the dictionary. Since it is known that the current character instance is highly correlated with the matched character, halftone images can be compressed using two methods
25.
JPEG Network Graphics
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JPEG Network Graphics is a JPEG-based graphics file format which is closely related to PNG, it uses the PNG file structure as a container format to wrap JPEG-encoded image data. JNG was created as an adjunct to the MNG animation format, JNG files embed an 8-bit or 12-bit JPEG datastream in order to store color data, and may embed another datastream for transparency information. Version 1.0 of the JNG specification was released on January 31,2001, usually, all the applications supporting the MNG file format can handle JNG files too. For example, Konqueror has native MNG/JNG support, and MNG/JNG plugins are available for Opera, Internet Explorer, the transparency information inside a JNG file can be saved either in lossless PNG format or in lossy JPEG format. This way, users can benefit from the power of JPEG compression while preserving lossless transparency information, the chunk-based structure of JNG files is essentially the same as that of PNG files, differing only in the slightly different signature and the use of different chunks. JNG does not have a registered Internet media type, but image/x-jng can be used.0 specification Photoshop Plugin Amiga Datatype
