Okular is the document viewer for KDE SC 4 (although it does not require the full KDE desktop). It is based on KPDF

KPDF

KPDF is a free PDF reader based on Xpdf. It is integrated with the KDE platform, so it embeds very well in Konqueror as KPart. Nevertheless, KPDF has been replaced in KDE SC 4 by Okular.- Features :Feature highlights:...

 and it replaced KPDF, KGhostView, KFax

KFAX

KFAX is a radio station licensed to transmit from San Francisco, California and heard in the Bay Area. , the station is owned by Salem Communications, and programs a Christian-oriented talk-radio format.- As KJBS :...

, KFaxview and KDVI in KDE 4.
Its functionality can be easily embedded in other applications.

Okular was started for the Google Summer of Code

Google Summer of Code

The Google Summer of Code is an annual program, first held from May to August 2005, in which Google awards stipends to hundreds of students who successfully complete a requested free or open-source software coding project during the summer...

 of 2005; Piotr Szymański was the accepted student.

Okular was identified as a success story of the 2007 Season of Usability

OpenUsability

OpenUsability is a project to help usability experts coordinate with open source software projects to improve the software's interaction and usability. They have worked with projects such as GIMP and KDE.-History:...

. In this season the Okular toolbar mockup was created based on an analysis of other popular document viewers and a usage survey.

Okular has additional features, including commenting on pdf documents, highlighting and drawing lines, geometric shapes, adding textboxes, and stamps. You can extract the text to a text file. You can select parts to save them or copy as text or image to the clipboard. You can trim white page borders and set bookmarks.

It supports the following file formats:

• Portable Document Format
  Portable Document Format
  Portable Document Format is an open standard for document exchange. This file format, created by Adobe Systems in 1993, is used for representing documents in a manner independent of application software, hardware, and operating systems....
  
   (PDF) with the Poppler
  Poppler (software)
  In computing, Poppler is a free software library used to render PDF documents. It is used by the PDF viewers of the open source GNOME and KDE desktop environments, and its development is supported by freedesktop.org....
  
   backend
• PostScript
  PostScript
  PostScript is a dynamically typed concatenative programming language created by John Warnock and Charles Geschke in 1982. It is best known for its use as a page description language in the electronic and desktop publishing areas. Adobe PostScript 3 is also the worldwide printing and imaging...
  
   with the libgs backend (Okular 0.6/KDE 4.0) / libspectre backend (Okular >= 0.7/KDE >= 4.1)
• Tagged Image File Format
  Tagged Image File Format
  TIFF is a file format for storing images, popular among graphic artists, the publishing industry, and both amateur and professional photographers in general. As of 2009, it is under the control of Adobe Systems...
  
   (TIFF) with the libTIFF
  Libtiff
  Libtiff is a library for reading and writing Tagged Image File Format files. The set also contains command line tools for processing TIFFs. It is distributed in source code and can be found as binary builds for all kinds of platforms...
  
   backend
• Microsoft Compiled HTML Help (CHM) with the libCHM backend
• DjVu
  DjVu
  DjVu is a computer file format designed primarily to store scanned documents, especially those containing a combination of text, line drawings, and photographs. It uses technologies such as image layer separation of text and background/images, progressive loading, arithmetic coding, and lossy...
  
   with the DjVuLibre backend
• Device independent file format (DVI)
• XML Paper Specification
  XML Paper Specification
  Open XML Paper Specification , is an open specification for a page description language and a fixed-document format originally developed by Microsoft as XML Paper Specification that was later standardized by Ecma International as international standard ECMA-388...
  
   (XPS)
• OpenDocument
  OpenDocument
  The Open Document Format for Office Applications is an XML-based file format for representing electronic documents such as spreadsheets, charts, presentations and word processing documents....
  
   format (ODF)
• FictionBook
  FictionBook
  FictionBook is an open XML-based e-book format, which originated and gained popularity in Russia. The FictionBook files have the .fb2 filename extension....
  
  
• ComicBook
• Plucker
  Plucker
  Plucker is an offline Web and free e-book reader for Palm OS based handheld devices, Windows Mobile devices and other PDAs. Plucker contains POSIX tools, scripts and "conduits" which work on Unix, Linux, Mac OS X, and Microsoft Windows...
  
  
• EPUB
  EPUB
  EPUB is a free and open e-book standard by the International Digital Publishing Forum...
  
  
• Mobipocket
  Mobipocket
  Mobipocket SA is a French company incorporated in March 2000 which produces Mobipocket Reader software, an E-Book reader for some PDAs, phones and desktop operating systems....
  
  
• Various image formats.

See also

• List of PDF software
• Evince
  Evince
  Evince is a document viewer for PDF, PostScript, DjVu, TIFF and DVI designed for the GNOME desktop environment.The developers of Evince intended to replace the multiple GNOME document viewers with a single and simple application. The Evince motto sums up the project aim: "Simply a Document...
  
   - the counterpart PDF viewer for GNOME
  GNOME
  GNOME is a desktop environment and graphical user interface that runs on top of a computer operating system. It is composed entirely of free and open source software...
  
  .

External links

• Okular home page
• Okular user wiki