DJVU (/ˌdeɪʒɑːˈvuː/ DAY-zhah-VOO , like English "déjà vu " ) is a computer file format designed primarily to store scanned documents , especially those containing a combination of text, line drawings, indexed color images, and photographs. It uses technologies such as image layer separation of text and background/images, progressive loading , arithmetic coding , and lossy compression for bitonal (monochrome ) images. This allows high-quality, readable images to be stored in a minimum of space, so that they can be made available on the web .
Free browser plug-ins and desktop viewers from different developers are available from the djvu.org website. DjVu is supported by a number of multi-format document viewers and e-book reader software on Linux ( Okular , Evince ) and Windows ( SumatraPDF ).
* 1 History
* 2 Technical overview
* 2.1.1 Chunk types
* 2.2 Compression
* 3 Format licensing * 4 Support * 5 See also * 6 References * 7 External links
The DjVu library distributed as part of the open-source package DjVuLibre has become the reference implementation for the DjVu format. DjVuLibre has been maintained and updated by the original developers of DjVu since 2002.
The DjVu file format specification has gone through a number of revisions:
Revision history SUPPORT STATUS VERSION RELEASE DATE NOTES
Unsupported 1–19 1996–1999 Developmental versions by AT&T labs preceding the sale of the format to LizardTech .
Older, still supported Version 21 September 1999 Indirect storage format replaced. The searchable text layer was added.
Older, still supported Version 22 April 2001 Page orientation, color JB2
Unsupported Version 23 July 2002 CID chunk
Unsupported Version 24 February 2003 LTAnno chunk
Older, still supported Version 25 May 2003 NAVM chunk. Support for DjVu bookmarks (outlines) was added. Changes made by Versions 23 and 24 were made obsolete.
Current Version 26 April 2005 Text/line annotations
DjVu file format is based on the Interchange
Optionally, these shapes may be mapped to UTF-8 codes (either by hand or potentially by a text recognition system ) and stored in the DjVu file. If this mapping exists, it is possible to select and copy text.
Since JBIG2 was based on JB2, both compression methods have the same problems when performing lossy compression. Numbers may be substituted with similarly looking numbers (such as replacing 6 with 8) if the text was scanned at a low resolution prior to lossy compression.
DjVu is an open file format with patents. The file format specification is published, as well as source code for the reference library. The original authors distribute an open-source implementation named "DjVuLibre" under the GNU General Public License . The rights to the commercial development of the encoding software have been transferred to different companies over the years, including AT">
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