diff --git a/ANNOUNCE b/ANNOUNCE
index f1e472e..70a71e3 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,4 +1,4 @@
-Libpng 1.6.27 - December 29, 2016
+Libpng 1.6.28 - January 5, 2017
 
 This is a public release of libpng, intended for use in production codes.
 
@@ -7,32 +7,28 @@
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   libpng-1.6.27.tar.xz (LZMA-compressed, recommended)
-   libpng-1.6.27.tar.gz
+   libpng-1.6.28.tar.xz (LZMA-compressed, recommended)
+   libpng-1.6.28.tar.gz
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lpng1627.7z  (LZMA-compressed, recommended)
-   lpng1627.zip
+   lpng1628.7z  (LZMA-compressed, recommended)
+   lpng1628.zip
 
 Other information:
 
-   libpng-1.6.27-README.txt
-   libpng-1.6.27-LICENSE.txt
-   libpng-1.6.27-*.asc (armored detached GPG signatures)
+   libpng-1.6.28-README.txt
+   libpng-1.6.28-LICENSE.txt
+   libpng-1.6.28-*.asc (armored detached GPG signatures)
 
-Changes since the last public release (1.6.26):
-  Control ADLER32 checking with new PNG_IGNORE_ADLER32 option.
-  Removed the use of a macro containing the pre-processor 'defined'
-    operator.  It is unclear whether this is valid; a macro that
-    "generates" 'defined' is not permitted, but the use of the word
-    "generates" within the C90 standard seems to imply more than simple
-    substitution of an expression itself containing a well-formed defined
-    operation.
-  Added ARM support to CMakeLists.txt (Andreas Franek).
-  Fixed a potential null pointer dereference in png_set_text_2() (bug report
-    and patch by Patrick Keshishian).
+Changes since the last public release (1.6.27):
+  Fixed arm/aarch64 detection in CMakeLists.txt (Gianfranco Costamagna).
+  Added option to Cmake build allowing a custom location of zlib to be
+    specified in a scenario where libpng is being built as a subproject
+    alongside zlib by another project (Sam Serrels).
+  Changed png_ptr->options from a png_byte to png_uint_32, to accomodate
+    up to 16 options.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index f4636ee..0b5e944 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5772,7 +5772,27 @@
 
 Version 1.6.27 [December 29, 2016]
   Fixed a potential null pointer dereference in png_set_text_2() (bug report
-    and patch by Patrick Keshishian).
+    and patch by Patrick Keshishian, CVE-2016-10087).
+
+Version 1.6.28rc01 [January 3, 2017]
+  Fixed arm/aarch64 detection in CMakeLists.txt (Gianfranco Costamagna).
+  Added option to Cmake build allowing a custom location of zlib to be
+    specified in a scenario where libpng is being built as a subproject
+    alongside zlib by another project (Sam Serrels).
+  Changed png_ptr->options from a png_byte to png_uint_32, to accomodate
+    up to 16 options.
+
+Version 1.6.28rc02 [January 4, 2017]
+  Added "include(GNUInstallDirs)" to CMakeLists.txt (Gianfranco Costamagna).
+  Moved SSE2 optimization code into the main libpng source directory.
+    Configure libpng with "configure --enable-intel-sse" or compile
+    libpng with "-DPNG_INTEL_SSE" in CPPFLAGS to enable it.
+
+Version 1.6.28rc03 [January 4, 2017]
+  Backed out the SSE optimization and last CMakeLists.txt to allow time for QA.
+
+Version 1.6.28 [January 5, 2017]
+  No changes.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 40b3503..e076d5e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -36,13 +36,20 @@
 
 set(PNGLIB_MAJOR 1)
 set(PNGLIB_MINOR 6)
-set(PNGLIB_RELEASE 27)
+set(PNGLIB_RELEASE 28)
 set(PNGLIB_NAME libpng${PNGLIB_MAJOR}${PNGLIB_MINOR})
 set(PNGLIB_VERSION ${PNGLIB_MAJOR}.${PNGLIB_MINOR}.${PNGLIB_RELEASE})
 
 # needed packages
-find_package(ZLIB REQUIRED)
-include_directories(${ZLIB_INCLUDE_DIR})
+
+#Allow users to specify location of Zlib, 
+# Useful if zlib is being built alongside this as a sub-project
+option(PNG_BUILD_ZLIB "Custom zlib Location, else find_package is used" OFF)
+
+IF(NOT PNG_BUILD_ZLIB)
+  find_package(ZLIB REQUIRED)
+  include_directories(${ZLIB_INCLUDE_DIR})
+ENDIF(NOT PNG_BUILD_ZLIB)
 
 if(NOT WIN32)
   find_library(M_LIBRARY
@@ -71,7 +78,8 @@
 set(DFA_XTRA "" CACHE FILEPATH "File containing extra configuration settings")
 
 # set definitions and sources for arm
-if(${CMAKE_SYSTEM_PROCESSOR} MATCHES "^arm")
+if(${CMAKE_SYSTEM_PROCESSOR} MATCHES "^arm" OR
+  ${CMAKE_SYSTEM_PROCESSOR} MATCHES "^aarch64")
   set(PNG_ARM_NEON_POSSIBLE_VALUES check on off)
   set(PNG_ARM_NEON "check" CACHE STRING "Enable ARM NEON optimizations:
      check: (default) use internal checking code;
@@ -727,7 +735,7 @@
 # SET UP LINKS
 if(PNG_SHARED)
   set_target_properties(png PROPERTIES
-#   VERSION 16.${PNGLIB_RELEASE}.1.6.27
+#   VERSION 16.${PNGLIB_RELEASE}.1.6.28
     VERSION 16.${PNGLIB_RELEASE}.0
     SOVERSION 16
     CLEAN_DIRECT_OUTPUT 1)
diff --git a/LICENSE b/LICENSE
index 32c480c..912552e 100644
--- a/LICENSE
+++ b/LICENSE
@@ -10,8 +10,8 @@
 
 This code is released under the libpng license.
 
-libpng versions 1.0.7, July 1, 2000 through 1.6.27, December 29, 2016 are
-Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
+libpng versions 1.0.7, July 1, 2000 through 1.6.28, January 5, 2017 are
+Copyright (c) 2000-2002, 2004, 2006-2017 Glenn Randers-Pehrson, are
 derived from libpng-1.0.6, and are distributed according to the same
 disclaimer and license as libpng-1.0.6 with the following individuals
 added to the list of Contributing Authors:
@@ -22,6 +22,7 @@
    Cosmin Truta
    Gilles Vollant
    James Yu
+   Mandar Sahastrabuddhe
 
 and with the following additions to the disclaimer:
 
@@ -127,4 +128,4 @@
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-December 29, 2016
+January 5, 2017
diff --git a/README b/README
index 87e5d1f..67b579d 100644
--- a/README
+++ b/README
@@ -1,4 +1,4 @@
-README for libpng version 1.6.27 - December 29, 2016 (shared library 16.0)
+README for libpng version 1.6.28 - January 5, 2017 (shared library 16.0)
 See the note about version numbers near the top of png.h
 
 See INSTALL for instructions on how to install libpng.
diff --git a/configure.ac b/configure.ac
index 315b2b2..8c474a6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -25,7 +25,7 @@
 
 dnl Version number stuff here:
 
-AC_INIT([libpng],[1.6.27],[png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.28],[png-mng-implement@lists.sourceforge.net])
 AC_CONFIG_MACRO_DIR([scripts])
 
 # libpng does not follow GNU file name conventions (hence 'foreign')
@@ -46,10 +46,10 @@
 dnl AM_PREREQ([1.11.2])
 dnl stop configure from automagically running automake
 
-PNGLIB_VERSION=1.6.27
+PNGLIB_VERSION=1.6.28
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
-PNGLIB_RELEASE=27
+PNGLIB_RELEASE=28
 
 dnl End of version number stuff
 
diff --git a/libpng-manual.txt b/libpng-manual.txt
index 457a5c6..048ba31 100644
--- a/libpng-manual.txt
+++ b/libpng-manual.txt
@@ -1,6 +1,6 @@
 libpng-manual.txt - A description on how to use and modify libpng
 
- libpng version 1.6.27 - December 29, 2016
+ libpng version 1.6.28 - January 5, 2017
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2016 Glenn Randers-Pehrson
@@ -11,7 +11,7 @@
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.6.27 - December 29, 2016
+ libpng versions 0.97, January 1998, through 1.6.28 - January 5, 2017
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2016 Glenn Randers-Pehrson
 
@@ -5355,7 +5355,7 @@
 an official declaration.
 
 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.27 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.28 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 
 Libpng only has two year fields.  One is a 2-byte unsigned integer
diff --git a/libpng.3 b/libpng.3
index 2ef1821..27b673c 100644
--- a/libpng.3
+++ b/libpng.3
@@ -1,6 +1,6 @@
-.TH LIBPNG 3 "December 29, 2016"
+.TH LIBPNG 3 "January 5, 2017"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.27
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.28
 .SH SYNOPSIS
 \fB
 #include <png.h>\fP
@@ -510,7 +510,7 @@
 .SH LIBPNG.TXT
 libpng-manual.txt - A description on how to use and modify libpng
 
- libpng version 1.6.27 - December 29, 2016
+ libpng version 1.6.28 - January 5, 2017
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2016 Glenn Randers-Pehrson
@@ -521,7 +521,7 @@
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.6.27 - December 29, 2016
+ libpng versions 0.97, January 1998, through 1.6.28 - January 5, 2017
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2016 Glenn Randers-Pehrson
 
@@ -5865,7 +5865,7 @@
 an official declaration.
 
 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.27 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.28 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 
 Libpng only has two year fields.  One is a 2-byte unsigned integer
@@ -5963,11 +5963,11 @@
  ...
  1.0.19                  10    10019  10.so.0.19[.0]
  ...
- 1.2.56                  13    10256  12.so.0.56[.0]
+ 1.2.57                  13    10257  12.so.0.56[.0]
  ...
- 1.5.27                  15    10527  15.so.15.27[.0]
+ 1.5.28                  15    10528  15.so.15.28[.0]
  ...
- 1.6.27                  16    10627  16.so.16.27[.0]
+ 1.6.28                  16    10628  16.so.16.28[.0]
 
 Henceforth the source version will match the shared-library minor
 and patch numbers; the shared-library major version number will be
@@ -6023,7 +6023,7 @@
 
 Thanks to Frank J. T. Wojcik for helping with the documentation.
 
-Libpng version 1.6.27 - December 29, 2016:
+Libpng version 1.6.28 - January 5, 2017:
 Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
 Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
 
@@ -6048,8 +6048,8 @@
 
 This code is released under the libpng license.
 
-libpng versions 1.0.7, July 1, 2000 through 1.6.27, December 29, 2016 are
-Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
+libpng versions 1.0.7, July 1, 2000 through 1.6.28, January 5, 2017 are
+Copyright (c) 2000-2002, 2004, 2006-2017 Glenn Randers-Pehrson, are
 derived from libpng-1.0.6, and are distributed according to the same
 disclaimer and license as libpng-1.0.6 with the following individuals
 added to the list of Contributing Authors:
@@ -6060,6 +6060,7 @@
    Cosmin Truta
    Gilles Vollant
    James Yu
+   Mandar Sahastrabuddhe
 
 and with the following additions to the disclaimer:
 
@@ -6173,7 +6174,7 @@
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-December 29, 2016
+January 5, 2017
 
 .\" end of man page
 
diff --git a/libpngpf.3 b/libpngpf.3
index f61847e..585fd24 100644
--- a/libpngpf.3
+++ b/libpngpf.3
@@ -1,6 +1,6 @@
-.TH LIBPNGPF 3 "December 29, 2016"
+.TH LIBPNGPF 3 "January 5, 2017"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.27
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.28
 (private functions)
 .SH SYNOPSIS
 \fB#include \fI"pngpriv.h"
diff --git a/png.5 b/png.5
index 7229e1b..5be0059 100644
--- a/png.5
+++ b/png.5
@@ -1,4 +1,4 @@
-.TH PNG 5 "December 29, 2016"
+.TH PNG 5 "January 5, 2017"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
diff --git a/png.c b/png.c
index 2e05de1..78ce39f 100644
--- a/png.c
+++ b/png.c
@@ -1,8 +1,8 @@
 
 /* png.c - location for general purpose libpng functions
  *
- * Last changed in libpng 1.6.27 [December 29, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.28 [January 5, 2017]
+ * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -14,7 +14,7 @@
 #include "pngpriv.h"
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_27 Your_png_h_is_not_version_1_6_27;
+typedef png_libpng_version_1_6_28 Your_png_h_is_not_version_1_6_28;
 
 /* Tells libpng that we have already handled the first "num_bytes" bytes
  * of the PNG file signature.  If the PNG data is embedded into another
@@ -776,15 +776,15 @@
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-      "libpng version 1.6.27 - December 29, 2016" PNG_STRING_NEWLINE \
-      "Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson" \
+      "libpng version 1.6.28 - January 5, 2017" PNG_STRING_NEWLINE \
+      "Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson" \
       PNG_STRING_NEWLINE \
       "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
       "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
       PNG_STRING_NEWLINE;
 #  else
-   return "libpng version 1.6.27 - December 29, 2016\
-      Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson\
+   return "libpng version 1.6.28 - January 5, 2017\
+      Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
 #  endif
@@ -4260,11 +4260,11 @@
    if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
       (option & 1) == 0)
    {
-      int mask = 3 << option;
-      int setting = (2 + (onoff != 0)) << option;
-      int current = png_ptr->options;
+      png_uint_32 mask = 3 << option;
+      png_uint_32 setting = (2 + (onoff != 0)) << option;
+      png_uint_32 current = png_ptr->options;
 
-      png_ptr->options = (png_byte)(((current & ~mask) | setting) & 0xff);
+      png_ptr->options = (png_uint_32)(((current & ~mask) | setting) & 0xff);
 
       return (current & mask) >> option;
    }
diff --git a/png.h b/png.h
index 674e00d..e4cf032 100644
--- a/png.h
+++ b/png.h
@@ -1,9 +1,9 @@
 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.6.27, December 29, 2016
+ * libpng version 1.6.28, January 5, 2017
  *
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -12,7 +12,7 @@
  * Authors and maintainers:
  *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
  *   libpng versions 0.89, June 1996, through 0.96, May 1997: Andreas Dilger
- *   libpng versions 0.97, January 1998, through 1.6.27, December 29, 2016:
+ *   libpng versions 0.97, January 1998, through 1.6.28, January 5, 2017:
  *     Glenn Randers-Pehrson.
  *   See also "Contributing Authors", below.
  */
@@ -25,12 +25,8 @@
  *
  * This code is released under the libpng license.
  *
- * Some files in the "contrib" directory and some configure-generated
- * files that are distributed with libpng have other copyright owners and
- * are released under other open source licenses.
- *
- * libpng versions 1.0.7, July 1, 2000 through 1.6.27, December 29, 2016 are
- * Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
+ * libpng versions 1.0.7, July 1, 2000 through 1.6.28, January 5, 2017 are
+ * Copyright (c) 2000-2002, 2004, 2006-2017 Glenn Randers-Pehrson, are
  * derived from libpng-1.0.6, and are distributed according to the same
  * disclaimer and license as libpng-1.0.6 with the following individuals
  * added to the list of Contributing Authors:
@@ -52,10 +48,10 @@
  *    risk of satisfactory quality, performance, accuracy, and effort is with
  *    the user.
  *
- * Some files in the "contrib" directory have other copyright owners and
+ * Some files in the "contrib" directory and some configure-generated
+ * files that are distributed with libpng have other copyright owners and
  * are released under other open source licenses.
  *
- *
  * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
  * Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
  * libpng-0.96, and are distributed according to the same disclaimer and
@@ -66,9 +62,6 @@
  *    Glenn Randers-Pehrson
  *    Willem van Schaik
  *
- * Some files in the "scripts" directory have different copyright owners
- * but are also released under this license.
- *
  * libpng versions 0.89, June 1996, through 0.96, May 1997, are
  * Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
  * and are distributed according to the same disclaimer and license as
@@ -214,11 +207,11 @@
  *    ...
  *    1.0.19                  10    10019  10.so.0.19[.0]
  *    ...
- *    1.2.56                  13    10256  12.so.0.56[.0]
+ *    1.2.57                  13    10257  12.so.0.57[.0]
  *    ...
- *    1.5.27                  15    10527  15.so.15.27[.0]
+ *    1.5.28                  15    10527  15.so.15.28[.0]
  *    ...
- *    1.6.27                  16    10627  16.so.16.27[.0]
+ *    1.6.28                  16    10628  16.so.16.28[.0]
  *
  *    Henceforth the source version will match the shared-library major
  *    and minor numbers; the shared-library major version number will be
@@ -246,13 +239,13 @@
  * Y2K compliance in libpng:
  * =========================
  *
- *    December 29, 2016
+ *    January 5, 2017
  *
  *    Since the PNG Development group is an ad-hoc body, we can't make
  *    an official declaration.
  *
  *    This is your unofficial assurance that libpng from version 0.71 and
- *    upward through 1.6.27 are Y2K compliant.  It is my belief that
+ *    upward through 1.6.28 are Y2K compliant.  It is my belief that
  *    earlier versions were also Y2K compliant.
  *
  *    Libpng only has two year fields.  One is a 2-byte unsigned integer
@@ -314,8 +307,8 @@
  */
 
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.27"
-#define PNG_HEADER_VERSION_STRING " libpng version 1.6.27 - December 29, 2016\n"
+#define PNG_LIBPNG_VER_STRING "1.6.28"
+#define PNG_HEADER_VERSION_STRING " libpng version 1.6.28 - January 5, 2017\n"
 
 #define PNG_LIBPNG_VER_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@@ -323,7 +316,7 @@
 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
 #define PNG_LIBPNG_VER_MAJOR   1
 #define PNG_LIBPNG_VER_MINOR   6
-#define PNG_LIBPNG_VER_RELEASE 27
+#define PNG_LIBPNG_VER_RELEASE 28
 
 /* This should match the numeric part of the final component of
  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
@@ -354,7 +347,7 @@
  * version 1.0.0 was mis-numbered 100 instead of 10000).  From
  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
  */
-#define PNG_LIBPNG_VER 10627 /* 1.6.27 */
+#define PNG_LIBPNG_VER 10628 /* 1.6.28 */
 
 /* Library configuration: these options cannot be changed after
  * the library has been built.
@@ -464,7 +457,7 @@
 /* This triggers a compiler error in png.c, if png.c and png.h
  * do not agree upon the version number.
  */
-typedef char* png_libpng_version_1_6_27;
+typedef char* png_libpng_version_1_6_28;
 
 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
  *
diff --git a/pngconf.h b/pngconf.h
index d1b746a..5e8b40b 100644
--- a/pngconf.h
+++ b/pngconf.h
@@ -1,7 +1,7 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.6.27, December 29, 2016
+ * libpng version 1.6.28, January 5, 2017
  *
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
diff --git a/pngrutil.c b/pngrutil.c
index 36820cf..bee0ea1 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,7 +1,7 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.6.27 [December 29, 2016]
+ * Last changed in libpng 1.6.27 [January 5, 2017]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
diff --git a/pngstruct.h b/pngstruct.h
index 55516ea..749d7e3 100644
--- a/pngstruct.h
+++ b/pngstruct.h
@@ -1,8 +1,8 @@
 
 /* pngstruct.h - header file for PNG reference library
  *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.28 [January 5, 2017]
+ * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
@@ -353,7 +353,7 @@
 
 /* Options */
 #ifdef PNG_SET_OPTION_SUPPORTED
-   png_byte options;           /* On/off state (up to 4 options) */
+   png_uint_32 options;           /* On/off state (up to 16 options) */
 #endif
 
 #if PNG_LIBPNG_VER < 10700
diff --git a/pngtest.c b/pngtest.c
index 76d4b5f..f8f76bf 100644
--- a/pngtest.c
+++ b/pngtest.c
@@ -2088,4 +2088,4 @@
 #endif
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_27 Your_png_h_is_not_version_1_6_27;
+typedef png_libpng_version_1_6_28 Your_png_h_is_not_version_1_6_28;
diff --git a/projects/vstudio/README.txt b/projects/vstudio/README.txt
index 9cbcd69..9fd0f1d 100644
--- a/projects/vstudio/README.txt
+++ b/projects/vstudio/README.txt
@@ -1,7 +1,7 @@
 
 VisualStudio instructions
 
-libpng version 1.6.27 - December 29, 2016
+libpng version 1.6.28 - January 5, 2017
 
 Copyright (c) 2010,2013,2015 Glenn Randers-Pehrson
 
diff --git a/projects/vstudio/zlib.props b/projects/vstudio/zlib.props
index 211f508..e0e0d8f 100644
--- a/projects/vstudio/zlib.props
+++ b/projects/vstudio/zlib.props
@@ -2,7 +2,7 @@
 <!--
  * zlib.props - location of zlib source
  *
- * libpng version 1.6.27 - December 29, 2016
+ * libpng version 1.6.28 - January 5, 2017
  *
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  *
diff --git a/scripts/README.txt b/scripts/README.txt
index 01abe01..1fbdb2e 100644
--- a/scripts/README.txt
+++ b/scripts/README.txt
@@ -1,9 +1,9 @@
 
-Makefiles for  libpng version 1.6.27 - December 29, 2016
+Makefiles for  libpng version 1.6.28 - January 5, 2017
 
 pnglibconf.h.prebuilt       =>  Stores configuration settings
  makefile.linux    =>  Linux/ELF makefile
-                       (gcc, creates libpng16.so.16.1.6.27)
+                       (gcc, creates libpng16.so.16.1.6.28)
  makefile.gcc      =>  Generic makefile (gcc, creates static libpng.a)
  makefile.knr      =>  Archaic UNIX Makefile that converts files with
                        ansi2knr (Requires ansi2knr.c from
@@ -33,12 +33,12 @@
  makefile.os2      =>  OS/2 Makefile (gcc and emx, requires libpng.def)
  makefile.sco      =>  For SCO OSr5  ELF and Unixware 7 with Native cc
  makefile.sggcc    =>  Silicon Graphics (gcc,
-                       creates libpng16.so.16.1.6.27)
+                       creates libpng16.so.16.1.6.28)
  makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
  makefile.solaris  =>  Solaris 2.X makefile (gcc,
-                       creates libpng16.so.16.1.6.27)
+                       creates libpng16.so.16.1.6.28)
  makefile.so9      =>  Solaris 9 makefile (gcc,
-                       creates libpng16.so.16.1.6.27)
+                       creates libpng16.so.16.1.6.28)
  makefile.std      =>  Generic UNIX makefile (cc, creates static libpng.a)
  makefile.sunos    =>  Sun makefile
  makefile.32sunu   =>  Sun Ultra 32-bit makefile
diff --git a/scripts/def.c b/scripts/def.c
index 67dbe6e..9939612 100644
--- a/scripts/def.c
+++ b/scripts/def.c
@@ -21,7 +21,7 @@
 PNG_DFN "OS2 CODE PRELOAD MOVEABLE DISCARDABLE"
 PNG_DFN ""
 PNG_DFN "EXPORTS"
-PNG_DFN ";Version 1.6.27"
+PNG_DFN ";Version 1.6.28"
 
 #define PNG_EXPORTA(ordinal, type, name, args, attributes)\
         PNG_DFN "@" SYMBOL_PREFIX "@@" name "@"
diff --git a/scripts/libpng-config-head.in b/scripts/libpng-config-head.in
index fbe3459..9b6b32b 100644
--- a/scripts/libpng-config-head.in
+++ b/scripts/libpng-config-head.in
@@ -11,7 +11,7 @@
 
 # Modeled after libxml-config.
 
-version=1.6.27
+version=1.6.28
 prefix=""
 libdir=""
 libs=""
diff --git a/scripts/libpng.pc.in b/scripts/libpng.pc.in
index 559cb30..f363b38 100644
--- a/scripts/libpng.pc.in
+++ b/scripts/libpng.pc.in
@@ -5,6 +5,6 @@
 
 Name: libpng
 Description: Loads and saves PNG files
-Version: 1.6.27
+Version: 1.6.28
 Libs: -L${libdir} -lpng16
 Cflags: -I${includedir}
diff --git a/scripts/makefile.cegcc b/scripts/makefile.cegcc
index 80b38d7..0fe9eac 100644
--- a/scripts/makefile.cegcc
+++ b/scripts/makefile.cegcc
@@ -23,7 +23,7 @@
 
 VERMAJ = 1
 VERMIN = 6
-VERMIC = 27
+VERMIC = 28
 VER = $(VERMAJ).$(VERMIN).$(VERMIC)
 NAME = libpng
 PACKAGE = $(NAME)-$(VER)
diff --git a/scripts/makefile.linux b/scripts/makefile.linux
index bdf25c4..ccb866a 100644
--- a/scripts/makefile.linux
+++ b/scripts/makefile.linux
@@ -10,7 +10,7 @@
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 27
+RELEASE = 28
 
 # Shared library names:
 LIBSO=$(LIBNAME).so
diff --git a/scripts/makefile.msys b/scripts/makefile.msys
index 9baaeb1..72c31c1 100644
--- a/scripts/makefile.msys
+++ b/scripts/makefile.msys
@@ -18,7 +18,7 @@
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 27
+RELEASE = 28
 
 # Shared library names:
 LIBSO=$(LIBNAME).dll
diff --git a/scripts/makefile.ne12bsd b/scripts/makefile.ne12bsd
index 305c79f..4fddc77 100644
--- a/scripts/makefile.ne12bsd
+++ b/scripts/makefile.ne12bsd
@@ -17,7 +17,7 @@
 
 LIB=	png16
 SHLIB_MAJOR=	0
-SHLIB_MINOR=	1.6.27
+SHLIB_MINOR=	1.6.28
 SRCS=	png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 	pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 	pngwtran.c pngmem.c pngerror.c pngpread.c
diff --git a/scripts/makefile.netbsd b/scripts/makefile.netbsd
index 3c0d170..4688b62 100644
--- a/scripts/makefile.netbsd
+++ b/scripts/makefile.netbsd
@@ -17,7 +17,7 @@
 
 LIB=	png
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.27
+SHLIB_MINOR=	1.6.28
 SRCS=	png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 	pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 	pngwtran.c pngmem.c pngerror.c pngpread.c
diff --git a/scripts/makefile.openbsd b/scripts/makefile.openbsd
index a6441f7..ba9def3 100644
--- a/scripts/makefile.openbsd
+++ b/scripts/makefile.openbsd
@@ -11,7 +11,7 @@
 MANDIR= ${PREFIX}/man/cat
 
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.27
+SHLIB_MINOR=	1.6.28
 
 LIB=	png
 SRCS=	png.c pngerror.c pngget.c pngmem.c pngpread.c \
diff --git a/scripts/pnglibconf.h.prebuilt b/scripts/pnglibconf.h.prebuilt
index 48dbdb6..ee70573 100644
--- a/scripts/pnglibconf.h.prebuilt
+++ b/scripts/pnglibconf.h.prebuilt
@@ -1,8 +1,8 @@
-/* libpng 1.6.27 STANDARD API DEFINITION */
+/* libpng 1.6.28 STANDARD API DEFINITION */
 
 /* pnglibconf.h - library build configuration */
 
-/* Libpng version 1.6.27 - December 29, 2016 */
+/* Libpng version 1.6.28 - January 5, 2017 */
 
 /* Copyright (c) 1998-2015 Glenn Randers-Pehrson */
 
diff --git a/scripts/symbols.def b/scripts/symbols.def
index d04f095..4ebe7d0 100644
--- a/scripts/symbols.def
+++ b/scripts/symbols.def
@@ -1,4 +1,4 @@
-;Version 1.6.27
+;Version 1.6.28
 ;--------------------------------------------------------------
 ; LIBPNG symbol list as a Win32 DEF file
 ; Contains all the symbols that can be exported from libpng