Barcode wouldn't be possible without a number of third-party libraries it uses. We are thankful to their respective authors for bringing those libraries. Here is the list in the alphabetical order.
(C) 2003-2013 by FreeImage This software uses the FreeImage open source image library. FreeImage is used under the FIPL, version 1.0 http://freeimage.sourceforge.net
Qt GUI Toolkit
Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies). Qt is available under the LGPL. http://qt-project.org/doc/qt-4.8/lgpl.html
Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies). All rights reserved. This file is part of a Qt Solutions component. Available under the BSD License http://qt.gitorious.org/qt-solutions/qt-solutions
Barcode uses ZINT backend code which is available under BSD 3 license. http://sourceforge.net/projects/zint/