If you modify libpng you may insert additional notices immediately following
this sentence.
-libpng versions 1.2.6, August 15, 2004, through 1.2.20, September 8, 2007, are
-Copyright (c) 2004, 2006-2007 Glenn Randers-Pehrson, and are
+This code is released under the libpng license.
+
+libpng versions 1.2.6, August 15, 2004, through 1.5.7, December 15, 2011, are
+Copyright (c) 2004, 2006-2011 Glenn Randers-Pehrson, and are
distributed according to the same disclaimer and license as libpng-1.2.5
with the following individual added to the list of Contributing Authors
Glenn Randers-Pehrson
glennrp at users.sourceforge.net
-September 8, 2007
+December 15, 2011