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ted changes upload file permanent link page information cite this page get shortened url switch to legacy parser print export download as pdf printable version in other projects wikimedia commons wikidata item appearance move to sidebar hide checked from wikipedia the free encyclopedia redirected from portable document format page version status this is an accepted version of this page this is the latest accepted revision reviewed on 10 september 2026 file format used to present documents for other uses see pdf disambiguation portable document format adobe pdf icon filename extension pdf internet media type application pdf 1 application x pdf application x bzpdf application x gzpdf type code pdf 1 including a single trailing space uniform type identifier uti com adobe pdf magic number pdf developed by adobe inc 1991 2008 iso 2008 initial release june 15 1993 33 years ago 1993 06 15 latest release 2 0 extended to pdf a pdf e pdf ua pdf vt pdf x standard iso 32000 2 open format yes website iso org standard 75839 html portable document format pdf standardized as iso 32000 is a file format developed by adobe in 1993 used to present documents including text formatting and images in a manner independent of application software hardware and operating systems 2 3 based on the postscript language a pdf file encapsulates a complete description of a fixed layout document including the text fonts vector graphics raster images and other information needed to display it pdf has its roots in the camelot project initiated by adobe co founder john warnock in 1991 4 pdf was standardized as iso 32000 in 2008 5 it is maintained by iso tc 171 sc 2 wg8 of which the pdf association is the committee manager 6 the last edition as iso 32000 2 2020 was published in december 2020 7 pdf files may contain a variety of content besides flat text and graphics including logical structuring elements interactive elements such as annotations and form fields layers rich media including video content three dimensional objects using u3d or prc and various other data formats the pdf specification also provides for encryption and digital signatures file attachments and metadata to enable workflows requiring these features history edit main article history of pdf the development of pdf began in 1991 when john warnock wrote a paper for a project then code named camelot in which he proposed the creation of a simplified version of postscript called interchange postscript ips 8 unlike traditional postscript which was tightly focused on rendering print jobs to output devices ips would be optimized for displaying pages to any screen and any platform 8 adobe made the pdf specification available free of charge in 1993 9 in the early years pdf was popular mainly in desktop publishing workflows and competed with several other formats including djvu envoy common ground digital paper farallon replica and even adobe s own postscript format pdf was a proprietary format controlled by adobe until it was released as an open standard on july 1 2008 and published by the international organization for standardization as iso 32000 1 2008 10 11 at which time control of the specification passed to an iso committee of volunteer industry experts in 2008 adobe published a public patent license to iso 32000 1 granting royalty free rights for all patents owned by adobe necessary to make use sell and distribute pdf compliant implementations 12 pdf 1 7 the sixth edition of the pdf specification that became iso 32000 1 includes some proprietary technologies defined by adobe such as adobe xml forms architecture xfa and a javascript extension for acrobat which are referenced by iso 32000 1 as normative and indispensable for the full implementation of the iso 32000 1 specification 13 these proprietary technologies are not standardized and their specification is published only on adobe s website 14 15 16 many of them are not supported by third party implementations of pdf iso published version 2 0 of pdf iso 32000 2 in 2017 replacing the specification provided by adobe 17 in december 2020 the second edition of pdf 2 0 iso 32000 2 2020 was published with clarifications corrections and critical updates to normative references 18 iso 32000 2 does not include any proprietary technologies as normative references 19 in april 2023 the pdf association made iso 32000 2 available for download free of charge 17 technical details edit a pdf file is often a combination of vector graphics text and bitmap graphics the basic types of content in a pdf are typeset text stored as content streams i e not encoded in plain text vector graphics for illustrations and designs that consist of shapes and lines raster graphics for photographs and other types of images and other multimedia objects in later pdf revisions a pdf document can also support links inside document or web page forms javascript initially available as a plugin for acrobat 3 0 or any other types of embedded contents that can be handled using plug ins pdf combines three technologies an equivalent subset of the postscript page description programming language but in declarative form 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 postscript language edit postscript is a page description language run in an interpreter to generate an image 8 it can handle graphics and has standard features of programming languages such as branching and looping 8 pdf is a subset of postscript simplified to remove certain control flow features while graphics commands remain 8 postscript was originally designed for a drastically different use case transmission of one way linear print jobs in which the postscript interpreter would collect a series of commands until it encountered the showpage command then execute all the commands to render a page as a raster image to a printing device 20 postscript was not intended for long term storage and real time interactive rendering of electronic documents to computer monitors so there was no need to support anything other than consecutive rendering of pages 20 if there was an error in the final printed output the user would correct it at the application level and send a new print job in the form of an entirely new postscript file thus any given page in a postscript file could be accurately rendered only as the cumulative result of executing all preceding commands to draw all previous pages any of which could affect subsequent pages plus the commands to draw that particular page and there was no easy way to bypass that process to skip around to different pages 20 traditionally to go from postscript to pdf a source postscript file that is an executable program is used as the basis for generating postscript like pdf code see e g adobe distiller this is done by applying standard compiler techniques like loop unrolling inlining and removing unused branches resulting in code that is purely declarative and static 20 the result is then packaged into a container format together with all necessary dependencies for correct rendering external files graphics or fonts to which the document refers and compressed as a document format pdf has several advantages over postscript pdf contains only static declarative postscript code that can be processed as data and does not require a full program interpreter or compiler 20 this avoids the complexity and security risks of an engine with such a higher complexity level like display postscript pdf has supported transparent graphics since version 1 4 while standard postscript does not pdf enforces the rule that the code for any particular page cannot affect any other pages 20 that rule is strongly recommended for postscript code too but has to be implemented explicitly see e g the document structuring conventions as postscript is a full programming language that allows for such greater flexibilities and is not limited to the concepts of pages and documents all data required for rendering is included within the file itself improving portability 21 its disadvantages are standard desktop environments sometimes lack software to generate pdf whereas any application capable of printing a document can save it as a postscript file 22 not being a full programing language and any limitations associated with that 22 a sometimes larger file size 23 pdf since v1 6 supports embedding of interactive 3d documents 3d drawings can be embedded using u3d or prc and various other data formats 24 25 26 file format edit a pdf file is organized using ascii characters except for certain elements that may have binary content 27 the file starts with a header containing a magic number as a readable string and the version of the format for example pdf 1 7 the format is a subset of a cos carousel object structure format 28 a cos tree file consists primarily of objects of which there are nine types 19 boolean values representing true or false real numbers integers strings enclosed within parentheses or represented as hexadecimal within single angle brackets strings may contain 8 bit characters names starting with a forward slash arrays ordered collections of objects enclosed within square brackets dictionaries collections of objects indexed by names enclosed within double angle brackets streams usually containing large amounts of optionally compressed binary data preceded by a dictionary and enclosed between the stream and endstream keywords the null object comments using 8 bit characters prefixed with the percent sign may be inserted objects may be either direct embedded in another object or indirect indirect objects are numbered with an object number and a generation number and defined between the obj and endobj keywords if residing in the document root beginning with pdf version 1 5 indirect objects except other streams may also be located in special streams known as object streams marked type objstm this technique enables non stream objects to have standard stream filters applied to them reduces the size of files that have large numbers of small indirect objects and is especially useful for tagged pdf object streams do not support specifying an object s generation number other than 0 an index table also called the cross reference table is located near the end of the file and gives the byte offset of each indirect object from the start of the file 29 this design allows for efficient random access to the objects in the file and also allows for small changes to be made without rewriting the entire file incremental update before pdf version 1 5 the table would always be in a special ascii format be marked with the xref keyword and follow the main body composed of indirect objects version 1 5 introduced optional cross reference streams which have the form of a standard stream object possibly with filters applied such a stream may be used instead of the ascii cross reference table and contains the offsets and other information in binary format the format is flexible in that it allows for integer width specification using the w array so that for example a document not exceeding 64 kib in size may dedicate only 2 bytes for object offsets to ensure backward compatibility a hybrid reference pdf file may include both traditional cross reference tables and cross reference streams allowing older pdf processors to read the file while still taking advantage of the new features introduced in version 1 5 30 at the end of a pdf file is a footer containing the startxref keyword followed by an offset to the start of the cross reference table starting with the xref keyword or the cross reference stream object followed by the eof end of file marker if a cross reference stream is not being used the footer is preceded by the trailer keyword followed by a dictionary containing information that would otherwise be contained in the cross reference stream object s dictionary a reference to the root object of the tree structure also known as the catalog root the count of indirect objects in the cross reference table size other optional information within each page there are one or multiple content streams that describe the text vector and images being drawn on the page the content stream is stack based similar to postscript 31 there are two layouts to the pdf files non linearized not optimized and linearized optimized non linearized pdf files can be smaller than their linear counterparts though they are slower to access because portions of the data required to assemble pages of the document are scattered throughout the pdf file linearized pdf files also called optimized or web optimized pdf files are constructed in a manner that enables them to be read in a web browser plugin without waiting for the entire file to download since all objects required for the first page to display are optimally organized at the start of the file 32 pdf files may be optimized using adobe acrobat software or qpdf page dimensions are not limited by the format itself however adobe acrobat imposes a limit of 15 million by 15 million inches or 225 000 000 000 000 square inches 145 161 km 2 56 047 sq mi 2 1129 imaging model edit the basic design of how graphics are represented in pdf is very similar to that of postscript except for the use of transparency which was added in pdf 1 4 pdf graphics use a device independent cartesian coordinate system to describe the surface of a page a pdf page description can use a matrix to scale rotate or skew graphical elements a key concept in pdf is that of the graphics state which is a collection of graphical parameters that may be changed saved and restored by a page description pdf has as of version 2 0 25 graphics state properties of which some of the most important are the current transformation matrix ctm which determines the coordinate system the clipping path the color space the alpha constant which is a key component of transparency black point compensation control introduced in pdf 2 0 vector graphics edit as in postscript vector graphics in pdf are constructed with paths paths are usually composed of lines and cubic bézier curves but can also be constructed from the outlines of text unlike postscript pdf does not allow a single path to mix text outlines with lines and curves paths can be stroked filled filled then stroked or used for clipping strokes and fills can use any color set in the graphics state including patterns pdf supports several types of patterns the simplest is the tiling pattern in which a piece of artwork is specified to be drawn repeatedly this may be a colored tiling pattern with the colors specified in the pattern object or an uncolored tiling pattern which defers color specification to the time the pattern is drawn beginning with pdf 1 3 there is also a shading pattern which draws continuously varying colors the...
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