What is pdf format

PDF (Portable Document Format) is a file format developed by Adobe Systems in 1993 for file exchange.

PDF is mainly composed of three technologies: derived from PostScript; font embedding system; data compression and transmission system. Its advantages are that it is cross-platform, can retain the original format (Layout) of the file, is an open standard, and can freely develop PDF-compatible software on a royalty-free basis. It is an open standard and became the ISO 32000 international standard in December 2007.

Portable Document Format is an electronic file format. This file format has nothing to do with the operating system platform, that is to say, PDF files are universal whether they are in Windows, Unix or Apple's Mac OS operating system. This feature makes it an ideal document format for electronic document distribution and digital information dissemination on the Internet. More and more e-books, product descriptions, company announcements, online materials, and emails are beginning to use PDF format files. (Recommended learning: PHP video tutorial)

The purpose of Adobe’s PDF file format is to support cross-platform, multimedia integrated information publishing and release, especially to provide network information Release support. To achieve this purpose, PDF has many advantages that other electronic document formats cannot compare with. The PDF file format can encapsulate text, fonts, formats, colors, and graphics and images that are independent of device and resolution in one file. Files in this format can also contain electronic information such as hypertext links, sounds and dynamic images, support special-length files, and are highly integrated, secure and reliable.

For ordinary readers, e-books made with PDF have the texture and reading effect of paper books, and can realistically show the original appearance of the original book, and the display size can be adjusted arbitrarily, providing readers with personalized way of reading.

PDF files use industry-standard compression algorithms and are generally smaller than PostScript files, making them easier to transmit and store. It is also page-independent. A PDF file contains one or more "pages" and each page can be processed independently, which is especially suitable for multi-processor systems. In addition, a PDF file also contains the PDF format version used in the file, as well as the positioning information of some important structures in the file. It is precisely because of the various advantages of PDF files that they have gradually become the new favorite in the publishing industry.

Trend

Initially PDF was only seen as a page preview format, not a production format. However, the market felt otherwise, and market expectations shifted the focus of the format and thus the product. Various e-book readers flood the domestic and foreign markets and have replaced paper media in many areas. The decline in the reading rate of print media is largely due to the fact that readers have shifted their attention from print media to electronic reading materials. Although the sales volume of the electronic book market is far less than that of the traditional book market, it has strong development momentum. Most e-reader manufacturers have begun to support the PDF format in whole or in part. The most commonly used PDF e-readers on the market include Dangdang’s mobile reader, Zhangmen Technology’s Baiyue, Jiuyue.com’s September Reading, and the specially developed reader for Android phones.

Adobe announced on July 13, 2009 that PDF/Archive (PDF/A), a long-term storage format for electronic documents, has become an official Chinese national standard after being approved by the China National Standardization Administration Committee. It will be officially implemented on September 1, 2009. PDF format files have become a de facto industry standard for digital information.

ISO Standardization

Since 1995, Adobe has participated in a number of professional subsets created by ISO to publish technical specifications and PDF standards for specific industries and purposes (such as PDF/X or PDF/A) working group that collaborates with ISO in the process. The purpose of developing subsets of the full PDF specification is to remove those features that are not required or cause problems for specific uses and the use of some required features that are only optional (not mandatory) features in the full PDF specification.

On January 29, 2007, Adobe announced that it would release the complete PDF 1.7 specification to the American National Standards Institute (ANSI) and the Association for Enterprise Content Management (AIIM) for publication by the International Organization for Standardization (ISO). ISO will develop PDF specifications in future versions, and Adobe is only a member of the ISO technical committee.

The ISO standard for "full-featured PDF" is published under the official number ISO 32000. Full-featured PDF specification means more than just a subset of the Adobe PDF specification; in terms of ISO 32000-1, full-featured PDF includes every item defined by Adobe's PDF 1.7 specification. However, Adobe later released extensions that were not part of the ISO standard. Those are also proprietary features in the PDF specification and can only be used as additional specification references.

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