Leptonica <http://www.leptonica.com/> is released under the following license
(from <http://www.leptonica.com/about-the-license.html>).

/*====================================================================*
-  Copyright (C) 2001 Leptonica.  All rights reserved.
-  This software is distributed in the hope that it will be
-  useful, but with NO WARRANTY OF ANY KIND.
-  No author or distributor accepts responsibility to anyone for the
-  consequences of using this software, or for whether it serves any
-  particular purpose or works at all, unless he or she says so in
-  writing.  Everyone is granted permission to copy, modify and
-  redistribute this source code, for commercial or non-commercial
-  purposes, with the following restrictions: (1) the origin of this
-  source code must not be misrepresented; (2) modified versions must
-  be plainly marked as such; and (3) this notice may not be removed
-  or altered from any source or modified source distribution.
*====================================================================*/