| Revision as of 12:57, 10 July 2002 edit213.253.40.113 (talk) The PostScript-like graphics language used in PDF is not capabable of general-purpose computing functions, and it is simply a set of page-description codes using the same imaging model as PostScript.← Previous edit | Revision as of 10:22, 11 July 2002 edit undo216.94.11.2 (talk)No edit summaryNext edit → | ||
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| '''Portable Document Format''' ('''PDF''') is a ] |
'''Portable Document Format''' ('''PDF''') is a ] developed by ] for representing documents in a manner that is independent of the original application ], ], and ] used to create those documents. A PDF file can describe documents containing any combination of text, graphics, and images in a ] and resolution independent format. These documents can be one page or thousands of pages, very simple or extremely complex with a rich use of fonts, graphics, colour, and images. | ||
| PDF is primarly the combination of three technologies: | PDF is primarly the combination of three technologies: | ||
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| * a compresson system to bundle these elements into a single file. | * a compresson system to bundle these elements into a single file. | ||
| Unlike PostScript, PDF uses a state machine to represent graphics instead of a ]. That means that the process of turning PDF back into a graphic is a matter of reading the description, rather than running a program in the PS interpreter. Nevertheless the "commands" inside the PDF file are based on PS concepts, layout and measurement, and the source of many PDF files is in fact an original PS program. | |||
| The PostScript-like graphics language used in PDF is not capabable of general-purpose computing functions, and it is simply a set of page-description codes using the same imaging model as PostScript. | |||
| Essentially the PostScript-like PDF code (which refers to external items such as fonts and ] images) is generated into a tokenized form, any resources (fonts, images) the PostScript referred to are collected, and they are all compressed into a single file. | Essentially the PostScript-like PDF code (which refers to external items such as fonts and ] images) is generated into a tokenized form, any resources (fonts, images) the PostScript referred to are collected, and they are all compressed into a single file. | ||
Revision as of 10:22, 11 July 2002
Portable Document Format (PDF) is a file format developed by Adobe Systems for representing documents in a manner that is independent of the original application software, hardware, and operating system used to create those documents. A PDF file can describe documents containing any combination of text, graphics, and images in a device independent and resolution independent format. These documents can be one page or thousands of pages, very simple or extremely complex with a rich use of fonts, graphics, colour, and images.
PDF is primarly the combination of three technologies:
- a cut-down form of PostScript for generating the layout and graphics
- a font-embedding/replacement system to allow fonts to travel with the documents, and
- a compresson system to bundle these elements into a single file.
Unlike PostScript, PDF uses a state machine to represent graphics instead of a page description language. That means that the process of turning PDF back into a graphic is a matter of reading the description, rather than running a program in the PS interpreter. Nevertheless the "commands" inside the PDF file are based on PS concepts, layout and measurement, and the source of many PDF files is in fact an original PS program.
Essentially the PostScript-like PDF code (which refers to external items such as fonts and raster images) is generated into a tokenized form, any resources (fonts, images) the PostScript referred to are collected, and they are all compressed into a single file.
There are several advantages to the PDF format. One is that there is only a single small file to transfer, whereas with the same file in PostScript format one must send the additional materials on their own. In addition the PostScript code is already interpreted, so it is faster to display on the screen. Finally the PDF system includes a font-replacement strategy that ensures the document will be readable even if the end-user does not have the "proper" fonts installed.
External links:
See also:
This article (or an earlier version of it) contains material from FOLDOC.