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Encyclopedia > Portable Document Format
Portable Document Format (PDF)
File extension: .pdf
MIME type: application/pdf
Type code: 'PDF ' (including a single space)
Uniform Type Identifier: com.adobe.pdf
Magic: %PDF
Developed by: Adobe Systems

The Portable Document Format (PDF) is the file format created by Adobe Systems in 1993 for document exchange. PDF is used for representing two-dimensional documents in a device-independent and display resolution-independent fixed-layout document format. Each PDF file encapsulates a complete description of a 2-D document (and, with Acrobat 3-D, embedded 3-D documents) that includes the text, fonts, images, and 2-D vector graphics that compose the document. PDF is most commonly used to refer to a type of Portable Document Format in computing. ... Image File history File links No higher resolution available. ... A filename extension is a suffix to the name of a computer file applied to show its format. ... Multipurpose Internet Mail Extensions (MIME) is an Internet Standard that extends the format of e-mail to support: text in character sets other than US-ASCII; non-text attachments; multi-part message bodies; and header information in non-ASCII character sets. ... A type code is a mechanism used in pre-Mac OS X versions of the Macintosh operating system to denote a files format, in a manner similar to file extensions in other operating systems. ... A Uniform Type Identifier (UTI) is a string that uniquely identifies the type of a class of items. ... In computer programming, a magic number is a constant used to identify the file or data type employed. ... Adobe Systems (pronounced a-DOE-bee IPA: ) (NASDAQ: ADBE) (LSE: ABS) is an American computer software company headquartered in San Jose, California, USA. Adobe was founded in December 1982[1] by John Warnock and Charles Geschke, who established the company after leaving Xerox PARC in order to develop and sell... A file format is a particular way to encode information for storage in a computer file. ... Adobe Systems (pronounced a-DOE-bee IPA: ) (NASDAQ: ADBE) (LSE: ABS) is an American computer software company headquartered in San Jose, California, USA. Adobe was founded in December 1982[1] by John Warnock and Charles Geschke, who established the company after leaving Xerox PARC in order to develop and sell... Display standards comparison The display resolution of a digital television or computer display typically refers to the number of distinct pixels in each dimension that can be displayed. ... It has been suggested that Vector monitor be merged into this article or section. ...


PDF is an open standard, and is now being prepared for submission as an ISO standard.[1] This article or section cites very few or no references or sources. ... This article does not cite any references or sources. ...

Contents

History

When the PDF first came out in the early 1990s, its general adoption was slow.[2] At that time, the PDF-creation tools (Acrobat) and the viewing and printing software had to be bought. Early versions of PDF had no support for external hyperlinks, reducing its usefulness on the World Wide Web; the additional size of the PDF document compared to plain text meant significantly longer download times over the slower modems common at the time, and rendering the files was slow on less powerful machines. Additionally, there were competing formats such as Envoy, Common Ground Digital Paper and even Adobe's own PostScript format (.ps); in those early years, the PDF file was mainly popular in desktop publishing workflow. How in the world are you ppl so fast. ... WWWs historical logo designed by Robert Cailliau The World Wide Web (commonly shortened to the Web) is a system of interlinked, hypertext documents accessed via the Internet. ... A modem (from modulate and demodulate) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. ... In computing, Envoy was a portable document file format marketed by WordPerfect Corporation, created as a competitor to Adobe Systems Portable Document Format (PDF). ... For the literary term, see Postscript. ... Adobe InDesign CS2, one of many popular desktop publishing applications. ... A workflow is a reliably repeatable pattern of activity enabled by a systematic organization of resources, defined roles and mass, energy and information flows, into a work process that can be documented and learned. ...


Adobe soon started free distribution of the Acrobat Reader (now Adobe Reader) program, and continued supporting the original PDF, which eventually became the de facto standard for printable documents. De facto is a Latin expression that means in fact or in practice. It is commonly used as opposed to de jure (meaning by law) when referring to matters of law or governance or technique (such as standards), that are found in the common experience as created or developed without...


The PDF file format has changed several times, as new versions of Adobe Acrobat have been released. There have been eight versions of PDF: 1.0 (1993), 1.1 (1994), 1.2 (1996), 1.3 (1999), 1.4 (2001), 1.5 (2003), 1.6 (2005), and 1.7 (2006), corresponding to Acrobat releases 1.0 to 8.0.


Technology

Anyone may create applications that read and write PDF files without having to pay royalties to Adobe Systems; Adobe holds patents to PDF, but licenses them for royalty-free use in developing software complying with its PDF specification.[3] Adobe Systems (pronounced a-DOE-bee IPA: ) (NASDAQ: ADBE) (LSE: ABS) is an American computer software company headquartered in San Jose, California, USA. Adobe was founded in December 1982[1] by John Warnock and Charles Geschke, who established the company after leaving Xerox PARC in order to develop and sell...


The PDF combines three technologies:

  • A sub-set of the PostScript page description programming language, for generating the layout and graphics.
  • A font-embedding/replacement system to allow fonts to travel with the documents.
  • A structured storage system to bundle these elements and any associated content into a single file, with data compression where appropriate.

For the literary term, see Postscript. ... “Source coding” redirects here. ...

PostScript

PostScript is a page description language run in an interpreter to generate an image, a process requiring many resources. PDF is a file format, not a programming language, i.e. flow control commands such as if and loop are removed, while graphics commands such as lineto remain. For the literary term, see Postscript. ... A page description language (PDL) is a language that describes the contents of a printed page in a higher level than an actual output bitmap. ... An interpreter is a computer program that executes other programs. ...


Often, the PostScript-like PDF code is generated from a source PostScript file. The graphics commands that are output by the PostScript code are collected and tokenized; any files, graphics, or fonts to which the document refers also are collected; then, everything is compressed to a single file. Therefore, the entire PostScript world (fonts, layout, measurements) remains intact. In computer science, lexical analysis is the process of converting a sequence of characters into a sequence of tokens. ...


As a document format, PDF has several advantages over PostScript:

  • PDF contains already tokenized and interpreted results of the PostScript source code, for direct correspondence between changes to items in the PDF page description and changes to the resulting page appearance.
  • PDF (from version 1.4) supports true graphic transparency, PostScript does not.
  • PostScript is an imperative programming language (with an implicit global state), so instructions accompanying the description of one page can affect the appearance of any following page. Therefore, all preceding pages must be processed in order to determine the correct appearance of a given page; each page in a PDF document is unaffected by the others.

Transparency is possible in a number of graphics file formats. ... In computer science, imperative programming, as opposed to declarative programming, is a programming paradigm that describes computation in terms of a program state and statements that change the program state. ...

Accessibility

PDF files can be created specifically to be accessible for disabled people. Current PDF file formats can include tags (XML), text equivalents, captions, audio descriptions, et cetera). Some software, such as Adobe InDesign, can automatically produce tagged PDFs. Leading screen readers, including JAWS, Window-Eyes, and Hal, can read tagged PDFs; current versions of the Acrobat and Acrobat Reader programs can also read PDFs aloud. Moreover, tagged PDFs can be re-flowed and magnified for readers with visual impairments. Problems remain with adding tags to older PDFs and those that are generated from scanned documents. In these cases, accessibility tags and re-flowing are unavailable, and must be created either manually or with OCR techniques. These processes are inaccessible to some disabled people. PDF/UA, the PDF/Universal Accessibility Committee, an activity of AIIM, is working on a specification for PDF accessibility based on the PDF 1.6 specification. The Extensible Markup Language (XML) is a general-purpose markup language. ... Adobe InDesign is a desktop publishing (DTP) application produced by Adobe Systems. ... A screen reader is a software application that attempts to identify and interpret what is being displayed on the screen. ... JAWS (an acronym for Job Access With Speech) is a screen reader, a software program for visually impaired users produced by the Blind and Low Vision Group at Freedom Scientific of St. ... Window-Eyes is a screen reader that makes a computer usable by someone who is blind or is visually impaired. ... Optical character recognition, usually abbreviated to OCR, is a type of computer software designed to translate images of handwritten or typewritten text (usually captured by a scanner) into machine-editable text, or to translate pictures of characters into a standard encoding scheme representing them (e. ... PDF/UA (PDF/Universal Accessibility) is a Standards Committee formed by AIIM. The mission of PDF/UA is to develop technical and other standards for the authoring, remediation and validation of PDF cotent to ensure accessibility. ... The Association for Information and Image Management or AIIM (pronounced aim) is an international industry association focused on enterprise content management (ECM). ...


One of the major problems with PDF accessibility is that PDF documents have three distinct views, which, depending on the document's creation, can be inconsistent with each other. The three views are (i) the physical view, (ii) the tags view, and (iii) the content view. The physical view is displayed and printed (what most people consider a PDF document). The tags view is what screen readers read (useful for people with poor eyesight). The content view is displayed when the document is re-flowed to Acrobat (useful for people with mobility disability). For a PDF document to be accessible, the three views must be consistent with each other.


Security

In 2001, PDF format attachments carrying viruses were first discovered. Virus researchers found that the PDF file viruses activated with Adobe Acrobat, but not with Acrobat Reader. As with all file formats, caution is advised. An up-to-date antivirus program is paramount.


Usage restrictions and monitoring

PDFs may be encrypted so that a password is needed to view or edit the contents. The PDF Reference defines both 40-bit and 128-bit encryption, both making use of a complex system of RC4 and MD5. The PDF Reference also defines ways in which third parties can define their own encryption systems for use in PDF. This article is about algorithms for encryption and decryption. ... In cryptography, RC4 (also known as ARC4 or ARCFOUR) is the most widely-used software stream cipher and is used in popular protocols such as Secure Sockets Layer (SSL) (to protect Internet traffic) and WEP (to secure wireless networks). ... In cryptography, MD5 (Message-Digest algorithm 5) is a widely used cryptographic hash function with a 128-bit hash value. ...


PDF files may also contain embedded DRM restrictions that provide further controls that limit copying, editing or printing. The restrictions on copying, editing, or printing depend on the reader software to obey them, so the security they provide is limited. Printable documents especially might be saved instead as bitmaps and subject to OCR. Digital rights management (DRM) is an umbrella term that refers to access control technologies used by publishers and other copyright holders to limit usage of digital media or devices. ...


The PDF Reference has technical details or see [1] for an end-user overview. Like HTML files, PDF files may submit information to a web server. This could be used to track the IP address of the client PC, a process known as phoning home. This article or section does not cite any references or sources. ... Phoning home is usually surreptitious communication between applications or hardware installed at end user sites and their manufacturers or developers. ...


Through their LiveCycle Policy Server product, Adobe provides a method to set security policies on specific documents. This can include requiring a user to authenticate and limiting the time frame a document can be accessed or amount of time a document can be opened while offline. Once a PDF document is tied to a policy server and a specific policy, that policy can be changed or revoked by the owner. This controls documents that are otherwise "in the wild." Each document open and close event can also be tracked by the policy server. Policy servers can be set up privately or Adobe offers a public service through Adobe Online Services.


Subsets

Proper subsets of PDF have been, or are being, standardized under ISO for several constituencies: This article does not cite any references or sources. ...

  • PDF/X for the printing and graphic arts as ISO 15930 (working in ISO TC130)
  • PDF/A for archiving in corporate/government/library/etc environments as ISO 19005 (work done in ISO TC171)
  • PDF/E for exchange of engineering drawings (work done in ISO TC171)
  • PDF/UA for universally accessible PDF files

A PDF/H variant (PDF for Healthcare) is being developed.[4] However, it may consist more in a set of "best practices" than in a specific format or subset. PDF/X is an ISO defined subset of the PDF standard. ... ISO 19005-1:2005 is an ISO Standard that was published on October 1, 2005: Document Management - Electronic document file format for long term preservation - Part 1: Use of PDF 1. ... PDF/UA (PDF/Universal Accessibility) is a Standards Committee formed by AIIM. The mission of PDF/UA is to develop technical and other standards for the authoring, remediation and validation of PDF cotent to ensure accessibility. ...


Mars

According to a 7 December 2006 Government Computer News blog, Joab Jackson writes that Adobe is exploring an XML-based next-generation PDF codenamed Mars: http://www.gcn.com/blogs/tech/42740.html is the 341st day of the year (342nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... A code name or cryptonym is a word or name used clandestinely to refer to another name or word. ...


Adobe has published information about the Mars file format at http://www.adobe.com/go/mars and at http://labs.adobe.com/wiki/index.php/Mars.


The format of graphic elements of Mars is sometimes described simply as “SVG”, but according to the 0.8.0 draft specification (§7.4, §7.5) the format is actually merely similar to SVG: it contains both additions to and subtractions from SVG, so it is in general neither viewable by nor creatable with standard SVG tools: some things will look noticeably different between SVG viewers and Mars viewers. Scalable Vector Graphics (SVG) is an XML specification and file format for describing two-dimensional vector graphics, both static and animated. ...


Content

A PDF file is often a combination of vector graphics, text, and raster graphics. The basic types of content in a PDF are: It has been suggested that Vector monitor be merged into this article or section. ... Suppose the smiley face in the top left corner is an RGB bitmap image. ...

  • text stored as such
  • vector graphics for illustrations and designs that consist of shapes and lines
  • raster graphics for photographs and other types of image

In later PDF revisions, a PDF document can also support links (inside document or web page), forms, JavaScript (initially available as plugin for Acrobat 3.0), or any other types of embedded contents that can be handled using plug-ins.


PDF 1.6 supports interactive 3D documents embedded in the PDF.


Two PDF files which look similar on a computer screen may be of very different sizes. For example, a high resolution raster image takes more space than a low resolution one. Typically higher resolution is needed for printing documents than for displaying them on screen. Other things that may increase the size of a file is embedding full fonts, especially for Asiatic scripts, and storing text as graphics.


Base 14 Fonts

There are fourteen typefaces that have a special significance to PDF documents: Times Roman (in standard, italic, bold, and bold oblique), Courier (in standard, oblique, bold and bold oblique), Helvetica (in standard, oblique, bold and bold oblique), Symbol and Zapf Dingbats. These should always be present (actually present or a close substitute) and so need not be embedded in a PDF. [2] PDF viewers must know about the metrics of these fonts. Other fonts may be substituted if they are not embedded in a PDF. Times New Roman is a serif typeface commissioned by The Times (London) newspaper in 1931 and designed by Stanley Morison together with Starling Burgess and Victor Lardent. ... Courier is a monospace slab serif font that resembles the output from a typewriter. ... This article is about the typeface Helvetica. ... Wikipedia does not have an article with this exact name. ...


Versions

PDF Version Year of Publication new features supported by Adobe Reader version
1.2 FlateDecode Acrobat Reader 3.0
1.3 2000 Acrobat Reader 4.0
1.4 2001 JBIG2 Acrobat Reader 5.0
1.5 2003 JPEG2000 Adobe Reader 6.0
1.6 2004 Adobe Reader 7.0
1.7 2007 Adobe Reader 8.0

JBIG2 is an image compression standard for bi-level images, developed by the Joint Bi-level Image Experts Group. ... JPEG 2000 is a wavelet-based image compression standard. ...

Implementations

Readers for many platforms are available, such as Adobe Reader, Foxit, Preview, Xpdf, Evince, Okular, and KPDF; there are also front-ends for many platforms to Ghostscript. PDF readers are generally free. There are many software options for creating PDFs, including the PDF printing capability built in to Mac OS X, the multi-platform OpenOffice.org, Microsoft Office 2007 (an additional free download from Microsoft is required), Wordperfect since version 9, numerous PDF print drivers for Microsoft Windows, and Adobe Acrobat itself. There is also specialized software for editing PDF files. In computing, a platform describes some sort of framework, either in hardware or software, which allows software to run. ... Adobe Acrobat Reader running on Debian Adobe Acrobat was the first software to support Adobe Systems Portable Document Format. ... Foxit reader is a freely available PDF reader for Microsoft Windows and other systems. ... Preview is Mac OS Xs application for displaying images and Portable Document Format (PDF) documents. ... Xpdf is a free software PDF viewer for the X Window System and Motif. ... Evince is a free software document viewer for both Portable Document Format (PDF) and PostScript documents for the GNOME desktop environment. ... Okular will be the document viewer for KDE 4. ... For other uses, see KPDF (TV). ... Ghostscript is a suite of software based on an interpreter for Adobe Systems PostScript and Portable Document Format (PDF) page description languages. ... Mac OS X (IPA: ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... OpenOffice. ... The 2007 Microsoft Office system (also called Microsoft Office 2007) is the most recent version of Microsofts productivity suite. ... Windows redirects here. ... How in the world are you ppl so fast. ...


AGFA introduced and shipped Apogee, the very first prepress workflow system based on PDF in 1997.


PDF was selected as the "native" metafile format for Mac OS X, replacing the PICT format of the earlier Mac OS. The imaging model of the Quartz graphics layer of Mac OS X is based on the model common to Display PostScript and PDF, leading to the nickname "Display PDF". The Preview application can display PDF files, and the version of Safari in Mac OS X v10.4 can display PDF files as well. System-level support for PDF allows Mac OS X applications to create PDF documents automatically, provided they support the Print command. When taking a screenshot under Mac OS X versions 10.0 through 10.3, the image was also captured as a PDF; in 10.4 the default behaviour is set to capture as a PNG file, though this behaviour can be set back to PDF if required. Metafile is a generic term for a file formats that can store multiple types of data. ... For the ancient tribe that inhabited what is now Scotland, see the Picts. ... This article or section does not adequately cite its references or sources. ... Quartz is the marketing name of the proprietary graphics layer that sits on top of the open source Darwin core of Mac OS X. Quartz is part of the Core Graphics framework. ... NeXT Computer Inc. ... Safari is a web browser developed by Apple Inc. ... Mac OS X version 10. ... PNG may stand for: Persona non grata, literally meaning an unwelcome person, is a term used in diplomacy with a specialised and legally defined meaning. ...


Some printers also support direct PDF printing, which can interpret PDF data without external help. Currently, all PDF capable printers also support PostScript, but most PostScript printers do not support direct PDF printing.


See also

This list of PDF software includes links to articles on computer software used to manage PDF documents. ... Scalable Vector Graphics (SVG) is an XML specification and file format for describing two-dimensional vector graphics, both static and animated. ... The XML Paper Specification (XPS), formerly codenamed Metro, is a document storage and viewing specification developed by Microsoft. ... XSL Formatting Objects, or XSL-FO, is an XML markup language for document formatting which is most often used to generate PDFs. ...

References

  1. ^ Adobe Systems Inc (29 January 2007). Adobe to Release PDF for Industry Standardization. Retrieved on 2007-01-31.
  2. ^ Laurens Leurs. The history of PDF. Retrieved on 2007-05-03.
  3. ^ http://partners.adobe.com/public/developer/support/topic_legal_notices.html
  4. ^ AIIM (2006-10-20). New Best Practices Guide Addresses Exchange of Healthcare Information. Retrieved on 2007-03-09.

January 29 is the 29th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 31st day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 123rd day of the year (124th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 68th day of the year (69th in leap years) in the Gregorian calendar. ...

External links


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