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DjVu is a web-centric format and software platform for distributing
documents and images.
DjVu can advantageously replace PDF, PS, TIFF, JPEG, and GIF for
distributing scanned documents, digital documents, or high-resolution
pictures.
DjVu content downloads faster, displays and renders faster,
looks nicer on a screen, and consume less client resources than competing
formats. DjVu images display instantly and can be smoothly zoomed and
panned with no lengthy re-rendering.
DjVu is used by hundreds of academic,
commercial, governmental, and non-commercial web sites around the world.
DjVuLibre is an open source (GPL'ed) implementation of DjVu, including
viewers, browser plugins, decoders, simple encoders, and utilities.
Download the Latest Version |
DjVuLibre includes a standalone viewer,
a browser plug-in (for Mozilla, Firefox, Konqueror, Netscape, Galeon, and Opera),
and command line tools (decoders, encoders, utilities).
DjVuLibre works under Unix with X11.
Native plugins for MS Windows
and Mac OS X are freely available
from LizardTech Inc..
The new portable viewer
djview4
is available as a separate package.
Latest Release:
- version 3.5.28
- released 2020-11-20.
- Check out the full download page for previous versions.
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DjVu (pronounced "déjà vu") a set of compression technologies,
a file format, and a software platform for the delivery over the Web of
digital documents, scanned documents, and high resolution images.
DjVu documents download and display extremely quickly, and look exactly
the same on all platforms with no compatibility problems due to fonts,
colors, etc. DjVu can be seen as a superior alternative to
PDF and PostScript for digital documents, to TIFF (and PDF) for scanned
bitonal documents, to JPEG and JPEG2000 for photographs and pictures, and to
GIF for large palettized images. DjVu is the only Web format that is
practical for distributing high-resolution scanned documents in color.
No other format comes close.
Typical DjVu file sizes are as follows:
- bitonal scanned documents: 5 to 30KB per page at 300dpi (3 to 10 times smaller than PDF or TIFF)
- color scanned documents: 30 to 100KB per page at 300dpi (5 to 10 times smaller than JPEG).
- photos: 2 times smaller than JPEG, about the same as JPEG-2000, but the decoder/renderer
is progressive and has minimal memory requirements.
- palettized images: 2 times smaller than GIF (up to 10 times if it's mostly text).
- digital (non scanned) documents: between 1 and 3 times smaller than PDF or gzipped PS
(depending on the amount of pictures), but rendering, page flipping, zooming, panning
are incomparably faster, and the image quality on screen desplays is much better
(antialiased text, etc).
More importantly, all DjVu images render very quickly and can be smoothly zoomed and panned.
Pages of a document can be turned instantly, with no annoying delay.
DjVu is used by hundreds of academic,
commercial, governmental, and non-commercial web sites around the world to distribute
scanned documents, digital documents, and high-resolution photos.
A short technical description of DjVu is available here.
Demos, and general information about DjVu can be found at
DjVuZone.org,
or at LizardTech.com.
DjVu was originally developped at
AT&T Labs-Research.
In March 2000, AT&T sold DjVu to
LizardTech Inc. who
now distributes Windows/CE/Mac plug-ins, and commercial encoders.
DjVuLibre is an open source implementation of DjVu. See
the credits/history page for more
details.
A short technical description of DjVu is available here.
In short, DjVu is a multipage document format that can use a number of different
coder/decoders (codecs) to compress the individual chunks that compose an
images or a page. In fact, DjVu is really four compression techniques wrapped into one format:
- DjVuPhoto (aka IW44): A progressive, wavelet-based lossy compression
format for continuous-tone images (i.e. photos and pictures).
- DjVuBitonal (aka JB2): A lossless or lossy compression technique
for bitonal (black & white) or palettized images that is particularly
effective on images with repeated shapes (such as documents images
where the same character appears many times in the document).
- DjVuDocument: A technique for scanned color document that separates
images into a foreground layer that contains the text and line drawings,
and a background layer that contains the pictures and background textures.
The foreground is encoded with DjVuBitonal and the Background with DjVuPhoto.
- BZZ: A general-purpose data compression technique similar to bzip2.
Bzz is used to compress searchable text layers and other metadata
in DjVu documents.
DjVu can be seen as nicely complementing PNG
and MNG (which, unlike DjVu are lossless formats) in the areas of document
image compression and lossy photo compression. DjVuPhoto is a bit older, but
similar in spirit to JPEG-2000. It is on a par with JPEG-2000 in terms of
image quality and file size, but it compares favorably in terms of rendering
time and memory requirements. DjVuBitonal is better than MMR/GroupIV (used by
PDF, TIFF, and most fax machines) by about a factor of 3 to 10. It is also
better than the emerging standard JBIG2 by about 20%.
In an effort to promote DjVu as a Web standard, LizardTech's management was
enlightened enough to release the reference implementation of DjVu under
the GNU GPL in October 2000. DjVuLibre (pronounced like the
French "déjà vu libre", which means free DjVu), is an
enhanced version of that code maintained by the original inventors of DjVu.
It is compatible with version 3.5 of LizardTech's DjVu software suite.
DjVuLibre includes:
- A standalone DjVu viewer for Unix under X11 (based on the Qt library).
- A browser plugin that works with most Unix browsers, including:
Netscape-4.x, Netscape-6.x, Mozilla, Galeon, Konqueror, and Opera.
- A full-fledged wavelet-based compressor for pictures.
- A simple compressor for bitonal (black and white) scanned pages.
- A very simple compressor for scanned color pages.
- A compressor for palettized images (a la GIF/PNG).
- A full set of utilities to manipulate and assemble DjVu images and documents.
- A set of decoders to convert DjVu to a number of other formats.
- An up-to-date version of the C++ DjVu Reference Library
Windows and Mac versions of the viewer/plug-in, free Windows
compressors, and high-end commercial compressors and OCR engines are
available from LizardTech Inc..
The compressors provided here are slower, produce larger files (sometimes
with lower image quality) than the commercial compressors, but they do the job.
For those who like quick solutions without having to install software, a
variety of free web-based conversion services are also available, including
Any2DjVu and
Bib2Web.
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