
1- WHAT IS DJVU.
================

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. DjVu can be seen as superior alternative to PDF and
Postscript for digital documents, to TIFF (and PDF) for scanned documents, to
JPEG 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. 

- Palettized images: 
        2 times smaller than GIF,
        up to 10 times if there is text.

DjVu is used by hundreds of commercial, governmental, and non-commercial web
sites around the world to distribute scanned documents, digital documents, and
high-resolution photos.

Demos, and general information about DjVu can be found at 
http://www.djvuzone.org, or at http://www.lizardtech.com. 

DjVu was originally developed at AT&T Labs-Research. AT&T sold DjVu to
LizardTech Inc. in March 2000.



2- WHAT IS DJVULIBRE? 
=====================

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"), is an enhanced version of that code maintained by the original
inventors of DjVu. It is compatible with LizardTech's DjVu software v3.5.

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 compressor for palettized images (a la GIF). 

- 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, as well as commercial versions
of the compressors and OCR engines are available from LizardTech Inc.. The
compressors provided here are slower, produce larger files, and sometimes
lower quality images than the commercial compressors, but they do the job.

A variety of free web-based conversion services are also available, including
any2djvu.djvuzone.org, bib2web.djvuzone.org, and openlib.djvuzone.org.




