Liblouis is an open-source braille translator and back-translator
named in honor of Louis Braille. It features support for computer
and literary braille, supports contracted and uncontracted translation
for many languages and has support for hyphenation. New languages
can easily be added through tables that support a rule- or dictionary
based approach. Tools for testing and debugging tables are also
included. Liblouis also supports math braille (Nemeth and Marburg).
Liblouis has features to support screen-reading programs. This has led
to its use in two open-source screenreaders, NVDA and Orca. It
is also used in some commercial assistive technology applications for
example by ViewPlus.
Liblouis is based on the translation routines in the BRLTTY
screenreader for Linux. It has, however, gone far beyond these
routines. In Linux and Mac OSX it is a shared library, and in Windows
it is a DLL.
Liblouis is free software licensed under the GNU LGPLv2.1+ (see
the file COPYING.LESSER).
The command line tools, are licensed under the GNU GPLv3+ (see the
For documentation, see the liblouis documentation (either as info
file, html, txt or pdf) in the doc directory. For examples
of translation tables, see
chardefs.cti, and whatever other files they may include in the
tables directory. This directory contains tables for many languages.
The Nemeth files will only work with the sister library
After unpacking the distribution tarball go to the directory it creates.
You now have the choice to compile liblouis for either 16- or 32-bit
unicode. By default it is compiled for the former. To get 32-bit Unicode
run configure with
make and then
make install. You
must have root privileges for the installation step.
This will produce the liblouis library and the programs
(for testing the library),
checking translation tables),
lou_debug (for debugging translation
lou_translate (for extensive testing of forward and
backwards translation) and
lou_trace (for tracing if individual
translations). For more details see the liblouis documentation.
If you wish to have man pages for the programs you might want to
help2man before running configure.
If you want to run the test suite with
make check you should install
libyaml as that will enable extensive tests on the tables. If you
want to skip those tests you can do so by running
You can contribute to Liblouis in several different ways:
If you have comments, questions, or want to use your knowledge to
help others, come join the conversation on either the mailing list
or on IRC. You can reach us at firstname.lastname@example.org
or in channel #liblouis on irc:irc.oftc.net.
To report a problem or request a feature, please file an issue.
Of course, we welcome pull requests and patches.
Finally, if you want to see what we have for the future and learn more
about our release cycles, all this information is detailed on the
For notes on the newest and older releases see the file NEWS.
Liblouis was begun in 2002 largely as a business decision by
ViewPlus. They believed that they could never have good braille
except as part of an open source effort and knew that John Boyer was
dying to start just such a project. So ViewPlus did start it on the
agreement that they would give a small monthly stipend to John Boyer
that allowed him to pay for sighted assistants. While ViewPlus has not
contributed much to the coding, it certainly has contributed and
continues to contribute to liblouis through that support of John