diff --git a/ANNOUNCE b/ANNOUNCE
index 262ff11..f1e472e 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,4 +1,4 @@
-Libpng 1.6.26 - October 20, 2016
+Libpng 1.6.27 - December 29, 2016
 
 This is a public release of libpng, intended for use in production codes.
 
@@ -7,53 +7,32 @@
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   libpng-1.6.26.tar.xz (LZMA-compressed, recommended)
-   libpng-1.6.26.tar.gz
+   libpng-1.6.27.tar.xz (LZMA-compressed, recommended)
+   libpng-1.6.27.tar.gz
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lpng1626.7z  (LZMA-compressed, recommended)
-   lpng1626.zip
+   lpng1627.7z  (LZMA-compressed, recommended)
+   lpng1627.zip
 
 Other information:
 
-   libpng-1.6.26-README.txt
-   libpng-1.6.26-LICENSE.txt
-   libpng-1.6.26-*.asc (armored detached GPG signatures)
+   libpng-1.6.27-README.txt
+   libpng-1.6.27-LICENSE.txt
+   libpng-1.6.27-*.asc (armored detached GPG signatures)
 
-Changes since the last public release (1.6.25):
-
-  Fixed handling zero length IDAT in pngfix (bug report by Agostino Sarubbo,
-    bugfix by John Bowler).
-  Do not issue a png_error() on read in png_set_pCAL() because png_handle_pCAL
-    has allocated memory that libpng needs to free.
-  Conditionally compile png_set_benign_errors() in pngread.c and pngtest.c
-  Issue a png_benign_error instead of a png_error on ADLER32 mismatch
-    while decoding compressed data chunks.
-  Changed PNG_ZLIB_VERNUM to ZLIB_VERNUM in pngpriv.h, pngstruct.h, and
-    pngrutil.c.
-  If CRC handling of critical chunks has been set to PNG_CRC_QUIET_USE,
-    ignore the ADLER32 checksum in the IDAT chunk as well as the chunk CRCs.
-  Issue png_benign_error() on ADLER32 checksum mismatch instead of png_error().
-  Add tests/badcrc.png and tests/badadler.png to tests/pngtest.
-  Merged pngtest.c with libpng-1.7.0beta84/pngtest.c
-  Updated the documentation about CRC and ADLER32 handling.
-  Quieted 117 warnings from clang-3.8 in pngtrans.c, pngread.c,
-     pngwrite.c, pngunknown.c, and pngvalid.c.
-  Quieted the 144 remaining -Wconversion compiler warnings by
-    revising the png_isaligned() macro and trivial changes in png.c,
-    pngerror.c, pngget.c, pngmem.c, pngset.c, pngrtran.c, pngrutil.c,
-    pngwtran.c, pngwrite.c, and pngwutil.c.
-  Quieted (bogus?) clang warnings about "absolute value has no effect"
-    when PNG_USE_ABS is defined.
-  Fixed offsets in contrib/intel/intel_sse.patch
-  Changed integer constant 4294967294 to unsigned 4294967294U in pngconf.h
-    to avoid a signed/unsigned compare in the preprocessor.
-  Use zlib-1.2.8.1 inflateValidate() instead of inflateReset2() to
-    optionally avoid ADLER32 evaluation.
-  Cosmetic change, "ptr != 0" to "ptr != NULL" in png.c and pngrutil.c
-  Despammed email addresses (replaced "@" with " at ").
+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).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index 9dd82b4..f4636ee 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5754,6 +5754,26 @@
   Cosmetic change, "ptr != 0" to "ptr != NULL" in png.c and pngrutil.c
   Despammed email addresses (replaced "@" with " at ").
 
+Version 1.6.27beta01 [November 2, 2016]
+  Restrict the new ADLER32-skipping to IDAT chunks.  It broke iCCP chunk
+    handling: an erroneous iCCP chunk would throw a png_error and reject the
+    entire PNG image instead of rejecting just the iCCP chunk with a warning,
+    if built with zlib-1.2.8.1.
+
+Version 1.6.27rc01 [December 27, 2016]
+  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).
+
+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).
+
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
diff --git a/CMakeLists.txt b/CMakeLists.txt
index c7878f6..40b3503 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,6 +5,7 @@
 # Revised by Roger Lowman, 2009-2010
 # Revised by Clifford Yapp, 2011-2012
 # Revised by Roger Leigh, 2016
+# Revised by Andreas Franek, 2016
 
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
@@ -35,7 +36,7 @@
 
 set(PNGLIB_MAJOR 1)
 set(PNGLIB_MINOR 6)
-set(PNGLIB_RELEASE 26)
+set(PNGLIB_RELEASE 27)
 set(PNGLIB_NAME libpng${PNGLIB_MAJOR}${PNGLIB_MINOR})
 set(PNGLIB_VERSION ${PNGLIB_MAJOR}.${PNGLIB_MINOR}.${PNGLIB_RELEASE})
 
@@ -69,6 +70,35 @@
 set(PNG_PREFIX "" CACHE STRING "Prefix to add to the API function names")
 set(DFA_XTRA "" CACHE FILEPATH "File containing extra configuration settings")
 
+# set definitions and sources for arm
+if(${CMAKE_SYSTEM_PROCESSOR} MATCHES "^arm")
+  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;
+     off: disable the optimizations;
+     on: turn on unconditionally.")
+  set_property(CACHE PNG_ARM_NEON PROPERTY STRINGS
+     ${PNG_ARM_NEON_POSSIBLE_VALUES})
+  list(FIND PNG_ARM_NEON_POSSIBLE_VALUES ${PNG_ARM_NEON} index)
+  if(index EQUAL -1)
+    message(FATAL_ERROR
+      " PNG_ARM_NEON must be one of [${PNG_ARM_NEON_POSSIBLE_VALUES}]")
+  elseif(NOT ${PNG_ARM_NEON} STREQUAL "no")
+    set(libpng_arm_sources
+      arm/arm_init.c
+      arm/filter_neon.S
+      arm/filter_neon_intrinsics.c)
+      
+    if(${PNG_ARM_NEON} STREQUAL "on")
+      add_definitions(-DPNG_ARM_NEON_OPT=2)
+    elseif(${PNG_ARM_NEON} STREQUAL "check")
+      add_definitions(-DPNG_ARM_NEON_CHECK_SUPPORTED)
+    endif()
+  else()
+    add_definitions(-DPNG_ARM_NEON_OPT=0)
+  endif()
+endif()
+
 # SET LIBNAME
 set(PNG_LIB_NAME png${PNGLIB_MAJOR}${PNGLIB_MINOR})
 
@@ -359,6 +389,7 @@
   pngwrite.c
   pngwtran.c
   pngwutil.c
+  ${libpng_arm_sources}
 )
 set(pngtest_sources
   pngtest.c
@@ -696,7 +727,7 @@
 # SET UP LINKS
 if(PNG_SHARED)
   set_target_properties(png PROPERTIES
-#   VERSION 16.${PNGLIB_RELEASE}.1.6.26
+#   VERSION 16.${PNGLIB_RELEASE}.1.6.27
     VERSION 16.${PNGLIB_RELEASE}.0
     SOVERSION 16
     CLEAN_DIRECT_OUTPUT 1)
diff --git a/LICENSE b/LICENSE
index 08e3129..32c480c 100644
--- a/LICENSE
+++ b/LICENSE
@@ -10,7 +10,7 @@
 
 This code is released under the libpng license.
 
-libpng versions 1.0.7, July 1, 2000 through 1.6.26, October 20, 2016 are
+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
 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
@@ -127,4 +127,4 @@
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-October 20, 2016
+December 29, 2016
diff --git a/Makefile.am b/Makefile.am
index 356704d..fb209ed 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,7 +1,7 @@
 # Makefile.am, the source file for Makefile.in (and hence Makefile), is
 #
 # Copyright (c) 2004-2016 Glenn Randers-Pehrson
-# Last changed in libpng 1.6.25 [October 20, 2016]
+# Last changed in libpng 1.6.25 [September 1, 2016]
 #
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
diff --git a/README b/README
index 709c269..87e5d1f 100644
--- a/README
+++ b/README
@@ -1,4 +1,4 @@
-README for libpng version 1.6.26 - October 20, 2016 (shared library 16.0)
+README for libpng version 1.6.27 - December 29, 2016 (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/TODO b/TODO
index cdb9e1f..fe9de4b 100644
--- a/TODO
+++ b/TODO
@@ -7,7 +7,7 @@
 cHRM transformation.
 Remove setjmp/longjmp usage in favor of returning error codes. As a start on
   this, minimize the use of png_error(), replacing them with
-  png_warning(); return(0; or similar.
+  png_warning(); return(0); or similar.
 Palette creation.
 Add "grayscale->palette" transformation and "palette->grayscale" detection.
 Improved dithering.
@@ -24,7 +24,6 @@
   background and doing rgb-to-gray transformation.
 Investigate pre-incremented loop counters and other loop constructions.
 Add interpolated method of handling interlacing.
-Switch to the simpler zlib (zlib/libpng) license if legally possible.
 Extend pngvalid.c to validate more of the libpng transformations.
 
 */
diff --git a/configure.ac b/configure.ac
index 83183ab..315b2b2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,7 +1,7 @@
 # configure.ac
 
 # Copyright (c) 2004-2016 Glenn Randers-Pehrson
-# Last changed in libpng 1.6.25 [October 20, 2016]
+# Last changed in libpng 1.6.25 [September 1, 2016]
 
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
@@ -25,7 +25,7 @@
 
 dnl Version number stuff here:
 
-AC_INIT([libpng],[1.6.26],[png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.27],[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=1.6.26
+PNGLIB_VERSION=1.6.27
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
-PNGLIB_RELEASE=26
+PNGLIB_RELEASE=27
 
 dnl End of version number stuff
 
diff --git a/contrib/libtests/pngvalid.c b/contrib/libtests/pngvalid.c
index 9b85c3e..499801b 100644
--- a/contrib/libtests/pngvalid.c
+++ b/contrib/libtests/pngvalid.c
@@ -1,7 +1,7 @@
 
 /* pngvalid.c - validate libpng by constructing then reading png files.
  *
- * Last changed in libpng 1.6.26 [October 20, 2016]
+ * Last changed in libpng 1.6.27 [December 29, 2016]
  * Copyright (c) 2014-2016 John Cunningham Bowler
  *
  * This code is released under the libpng license.
@@ -4010,8 +4010,11 @@
 #  define do_own_interlace 1
 #endif /* WRITE_INTERLACING tests */
 
-#define CAN_WRITE_INTERLACE\
-   PNG_LIBPNG_VER >= 10700 || defined PNG_WRITE_INTERLACING_SUPPORTED
+#if PNG_LIBPNG_VER >= 10700 || defined PNG_WRITE_INTERLACING_SUPPORTED
+#   define CAN_WRITE_INTERLACE 1
+#else
+#   define CAN_WRITE_INTERLACE 0
+#endif
 
 /* Do the same thing for read interlacing; this controls whether read tests do
  * their own de-interlace or use libpng.
diff --git a/libpng-manual.txt b/libpng-manual.txt
index a5cd8ee..457a5c6 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 1.6.26 - October 20, 2016
+ libpng version 1.6.27 - December 29, 2016
  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 1.6.26 - October 20, 2016
+ libpng versions 0.97, January 1998, through 1.6.27 - December 29, 2016
  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 1.6.26 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.27 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 ce06bce..2ef1821 100644
--- a/libpng.3
+++ b/libpng.3
@@ -1,6 +1,6 @@
-.TH LIBPNG 3 "October 20, 2016"
+.TH LIBPNG 3 "December 29, 2016"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.26
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.27
 .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 1.6.26 - October 20, 2016
+ libpng version 1.6.27 - December 29, 2016
  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 1.6.26 - October 20, 2016
+ libpng versions 0.97, January 1998, through 1.6.27 - December 29, 2016
  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 1.6.26 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.27 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
@@ -5967,7 +5967,7 @@
  ...
  1.5.27                  15    10527  15.so.15.27[.0]
  ...
- 1.6.26                  16    10626  16.so.16.26[.0]
+ 1.6.27                  16    10627  16.so.16.27[.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 1.6.26 - October 20, 2016:
+Libpng version 1.6.27 - December 29, 2016:
 Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
 Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
 
@@ -6048,7 +6048,7 @@
 
 This code is released under the libpng license.
 
-libpng versions 1.0.7, July 1, 2000 through 1.6.26, October 20, 2016 are
+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
 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
@@ -6173,7 +6173,7 @@
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-October 20, 2016
+December 29, 2016
 
 .\" end of man page
 
diff --git a/libpngpf.3 b/libpngpf.3
index ed37924..f61847e 100644
--- a/libpngpf.3
+++ b/libpngpf.3
@@ -1,6 +1,6 @@
-.TH LIBPNGPF 3 "October 20, 2016"
+.TH LIBPNGPF 3 "December 29, 2016"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.26
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.27
 (private functions)
 .SH SYNOPSIS
 \fB#include \fI"pngpriv.h"
diff --git a/mips/filter_msa_intrinsics.c b/mips/filter_msa_intrinsics.c
index 5930ae3..943bb3d 100644
--- a/mips/filter_msa_intrinsics.c
+++ b/mips/filter_msa_intrinsics.c
@@ -3,7 +3,7 @@
  *
  * Copyright (c) 2016 Glenn Randers-Pehrson
  * Written by Mandar Sahastrabuddhe, August 2016.
- * Last changed in libpng 1.6.25 [October 20, 2016]
+ * Last changed in libpng 1.6.25 [September 1, 2016]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/mips/mips_init.c b/mips/mips_init.c
index 5bc79e6..0bfb7a3 100644
--- a/mips/mips_init.c
+++ b/mips/mips_init.c
@@ -3,7 +3,7 @@
  *
  * Copyright (c) 2016 Glenn Randers-Pehrson
  * Written by Mandar Sahastrabuddhe, 2016.
- * Last changed in libpng 1.6.25 [October 20, 2016]
+ * Last changed in libpng 1.6.25 [September 1, 2016]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/png.5 b/png.5
index bec6741..7229e1b 100644
--- a/png.5
+++ b/png.5
@@ -1,4 +1,4 @@
-.TH PNG 5 "October 20, 2016"
+.TH PNG 5 "December 29, 2016"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
diff --git a/png.c b/png.c
index 6d5633c..2e05de1 100644
--- a/png.c
+++ b/png.c
@@ -1,7 +1,7 @@
 
 /* png.c - location for general purpose libpng functions
  *
- * Last changed in libpng 1.6.26 [October 20, 2016]
+ * Last changed in libpng 1.6.27 [December 29, 2016]
  * 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.)
@@ -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_26 Your_png_h_is_not_version_1_6_26;
+typedef png_libpng_version_1_6_27 Your_png_h_is_not_version_1_6_27;
 
 /* 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
@@ -477,6 +477,7 @@
          png_free(png_ptr, info_ptr->text);
          info_ptr->text = NULL;
          info_ptr->num_text = 0;
+         info_ptr->max_text = 0;
       }
    }
 #endif
@@ -775,14 +776,14 @@
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-      "libpng version 1.6.26 - October 20, 2016" PNG_STRING_NEWLINE \
+      "libpng version 1.6.27 - December 29, 2016" PNG_STRING_NEWLINE \
       "Copyright (c) 1998-2002,2004,2006-2016 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 1.6.26 - October 20, 2016\
+   return "libpng version 1.6.27 - December 29, 2016\
       Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
diff --git a/png.h b/png.h
index f094463..674e00d 100644
--- a/png.h
+++ b/png.h
@@ -1,7 +1,7 @@
 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.6.26, October 20, 2016
+ * libpng version 1.6.27, December 29, 2016
  *
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -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 1.6.26, October 20, 2016:
+ *   libpng versions 0.97, January 1998, through 1.6.27, December 29, 2016:
  *     Glenn Randers-Pehrson.
  *   See also "Contributing Authors", below.
  */
@@ -29,7 +29,7 @@
  * 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 1.6.26, October 20, 2016 are
+ * 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
  * 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
@@ -218,7 +218,7 @@
  *    ...
  *    1.5.27                  15    10527  15.so.15.27[.0]
  *    ...
- *    1.6.26                  16    10626  16.so.16.26[.0]
+ *    1.6.27                  16    10627  16.so.16.27[.0]
  *
  *    Henceforth the source version will match the shared-library major
  *    and minor numbers; the shared-library major version number will be
@@ -246,13 +246,13 @@
  * Y2K compliance in libpng:
  * =========================
  *
- *    October 20, 2016
+ *    December 29, 2016
  *
  *    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 1.6.26 are Y2K compliant.  It is my belief that
+ *    upward through 1.6.27 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 +314,8 @@
  */
 
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.26"
-#define PNG_HEADER_VERSION_STRING " libpng version 1.6.26 - October 20, 2016\n"
+#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_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@@ -323,7 +323,7 @@
 /* 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 26
+#define PNG_LIBPNG_VER_RELEASE 27
 
 /* This should match the numeric part of the final component of
  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
@@ -354,7 +354,7 @@
  * 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 10626 /* 1.6.26 */
+#define PNG_LIBPNG_VER 10627 /* 1.6.27 */
 
 /* Library configuration: these options cannot be changed after
  * the library has been built.
@@ -464,7 +464,7 @@
 /* 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_26;
+typedef char* png_libpng_version_1_6_27;
 
 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
  *
@@ -3230,7 +3230,8 @@
 #ifdef PNG_MIPS_MSA_API_SUPPORTED
 #  define PNG_MIPS_MSA   6 /* HARDWARE: MIPS Msa SIMD instructions supported */
 #endif
-#define PNG_OPTION_NEXT  8 /* Next option - numbers must be even */
+#define PNG_IGNORE_ADLER32 8
+#define PNG_OPTION_NEXT  10 /* Next option - numbers must be even */
 
 /* Return values: NOTE: there are four values and 'off' is *not* zero */
 #define PNG_OPTION_UNSET   0 /* Unset - defaults to off */
diff --git a/pngconf.h b/pngconf.h
index 5c891eb..d1b746a 100644
--- a/pngconf.h
+++ b/pngconf.h
@@ -1,7 +1,7 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.6.26, October 20, 2016
+ * libpng version 1.6.27, December 29, 2016
  *
  * 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 fb5f5f0..36820cf 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,7 +1,7 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.6.26 [October 20, 2016]
+ * Last changed in libpng 1.6.27 [December 29, 2016]
  * 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.)
@@ -418,9 +418,10 @@
             png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
       }
 
-#if ZLIB_VERNUM >= 0x1281
-      /* Turn off validation of the ADLER32 checksum */
-      if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
+#if ZLIB_VERNUM >= 0x1281 && \
+   defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_IGNORE_ADLER32)
+      if (((png_ptr->options >> PNG_IGNORE_ADLER32) & 3) == PNG_OPTION_ON)
+         /* Turn off validation of the ADLER32 checksum in IDAT chunks */
          ret = inflateValidate(&png_ptr->zstream, 0);
 #endif
 
@@ -716,7 +717,7 @@
                    * the extra space may otherwise be used as a Trojan Horse.
                    */
                   if (ret == Z_STREAM_END &&
-                     chunklength - prefix_size != lzsize)
+                      chunklength - prefix_size != lzsize)
                      png_chunk_benign_error(png_ptr, "extra compressed data");
                }
 
@@ -826,7 +827,7 @@
       return Z_STREAM_ERROR;
    }
 }
-#endif
+#endif /* READ_iCCP */
 
 /* Read and check the IDHR chunk */
 
@@ -4107,15 +4108,7 @@
          png_zstream_error(png_ptr, ret);
 
          if (output != NULL)
-         {
-            if(!strncmp(png_ptr->zstream.msg,"incorrect data check",20))
-            {
-               png_chunk_benign_error(png_ptr, "ADLER32 checksum mismatch");
-               continue;
-            }
-            else
-               png_chunk_error(png_ptr, png_ptr->zstream.msg);
-         }
+            png_chunk_error(png_ptr, png_ptr->zstream.msg);
 
          else /* checking */
          {
diff --git a/pngtest.c b/pngtest.c
index dd558dd..76d4b5f 100644
--- a/pngtest.c
+++ b/pngtest.c
@@ -986,9 +986,14 @@
       /* Allow application (pngtest) errors and warnings to pass */
       png_set_benign_errors(read_ptr, 1);
 
-      /* Turn off CRC and ADLER32 checking while reading */
+      /* Turn off CRC checking while reading */
       png_set_crc_action(read_ptr, PNG_CRC_QUIET_USE, PNG_CRC_QUIET_USE);
 
+#ifdef PNG_IGNORE_ADLER32
+      /* Turn off ADLER32 checking while reading */
+      png_set_option(read_ptr, PNG_IGNORE_ADLER32, PNG_OPTION_ON);
+#endif
+
 # ifdef PNG_WRITE_SUPPORTED
       png_set_benign_errors(write_ptr, 1);
 # endif
@@ -2083,4 +2088,4 @@
 #endif
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_26 Your_png_h_is_not_version_1_6_26;
+typedef png_libpng_version_1_6_27 Your_png_h_is_not_version_1_6_27;
diff --git a/projects/vstudio/README.txt b/projects/vstudio/README.txt
index 643b763..9cbcd69 100644
--- a/projects/vstudio/README.txt
+++ b/projects/vstudio/README.txt
@@ -1,7 +1,7 @@
 
 VisualStudio instructions
 
-libpng version 1.6.26 - October 20, 2016
+libpng version 1.6.27 - December 29, 2016
 
 Copyright (c) 2010,2013,2015 Glenn Randers-Pehrson
 
diff --git a/projects/vstudio/zlib.props b/projects/vstudio/zlib.props
index b7ab242..211f508 100644
--- a/projects/vstudio/zlib.props
+++ b/projects/vstudio/zlib.props
@@ -2,7 +2,7 @@
 <!--
  * zlib.props - location of zlib source
  *
- * libpng version 1.6.26 - October 20, 2016
+ * libpng version 1.6.27 - December 29, 2016
  *
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  *
diff --git a/scripts/README.txt b/scripts/README.txt
index 71aeebe..01abe01 100644
--- a/scripts/README.txt
+++ b/scripts/README.txt
@@ -1,9 +1,9 @@
 
-Makefiles for  libpng version 1.6.26 - October 20, 2016
+Makefiles for  libpng version 1.6.27 - December 29, 2016
 
 pnglibconf.h.prebuilt       =>  Stores configuration settings
  makefile.linux    =>  Linux/ELF makefile
-                       (gcc, creates libpng16.so.16.1.6.26)
+                       (gcc, creates libpng16.so.16.1.6.27)
  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.16.1.6.26)
+                       creates libpng16.so.16.1.6.27)
  makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
  makefile.solaris  =>  Solaris 2.X makefile (gcc,
-                       creates libpng16.so.16.1.6.26)
+                       creates libpng16.so.16.1.6.27)
  makefile.so9      =>  Solaris 9 makefile (gcc,
-                       creates libpng16.so.16.1.6.26)
+                       creates libpng16.so.16.1.6.27)
  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 7f2be6a..67dbe6e 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 1.6.26"
+PNG_DFN ";Version 1.6.27"
 
 #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 b78f908..fbe3459 100644
--- a/scripts/libpng-config-head.in
+++ b/scripts/libpng-config-head.in
@@ -11,7 +11,7 @@
 
 # Modeled after libxml-config.
 
-version=1.6.26
+version=1.6.27
 prefix=""
 libdir=""
 libs=""
diff --git a/scripts/libpng.pc.in b/scripts/libpng.pc.in
index 7a2cb2b..559cb30 100644
--- a/scripts/libpng.pc.in
+++ b/scripts/libpng.pc.in
@@ -5,6 +5,6 @@
 
 Name: libpng
 Description: Loads and saves PNG files
-Version: 1.6.26
+Version: 1.6.27
 Libs: -L${libdir} -lpng16
 Cflags: -I${includedir}
diff --git a/scripts/makefile.cegcc b/scripts/makefile.cegcc
index 93c1236..80b38d7 100644
--- a/scripts/makefile.cegcc
+++ b/scripts/makefile.cegcc
@@ -23,7 +23,7 @@
 
 VERMAJ = 1
 VERMIN = 6
-VERMIC = 26
+VERMIC = 27
 VER = $(VERMAJ).$(VERMIN).$(VERMIC)
 NAME = libpng
 PACKAGE = $(NAME)-$(VER)
diff --git a/scripts/makefile.linux b/scripts/makefile.linux
index e7347f6..bdf25c4 100644
--- a/scripts/makefile.linux
+++ b/scripts/makefile.linux
@@ -10,7 +10,7 @@
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 26
+RELEASE = 27
 
 # Shared library names:
 LIBSO=$(LIBNAME).so
diff --git a/scripts/makefile.msys b/scripts/makefile.msys
index 09429ee..9baaeb1 100644
--- a/scripts/makefile.msys
+++ b/scripts/makefile.msys
@@ -18,7 +18,7 @@
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 26
+RELEASE = 27
 
 # Shared library names:
 LIBSO=$(LIBNAME).dll
diff --git a/scripts/makefile.ne12bsd b/scripts/makefile.ne12bsd
index 3d36688..305c79f 100644
--- a/scripts/makefile.ne12bsd
+++ b/scripts/makefile.ne12bsd
@@ -17,7 +17,7 @@
 
 LIB=	png16
 SHLIB_MAJOR=	0
-SHLIB_MINOR=	1.6.26
+SHLIB_MINOR=	1.6.27
 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 8fb2c76..3c0d170 100644
--- a/scripts/makefile.netbsd
+++ b/scripts/makefile.netbsd
@@ -17,7 +17,7 @@
 
 LIB=	png
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.26
+SHLIB_MINOR=	1.6.27
 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 35b1424..a6441f7 100644
--- a/scripts/makefile.openbsd
+++ b/scripts/makefile.openbsd
@@ -11,7 +11,7 @@
 MANDIR= ${PREFIX}/man/cat
 
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.26
+SHLIB_MINOR=	1.6.27
 
 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 ba7805f..48dbdb6 100644
--- a/scripts/pnglibconf.h.prebuilt
+++ b/scripts/pnglibconf.h.prebuilt
@@ -1,8 +1,8 @@
-/* libpng 1.6.26 STANDARD API DEFINITION */
+/* libpng 1.6.27 STANDARD API DEFINITION */
 
 /* pnglibconf.h - library build configuration */
 
-/* Libpng version 1.6.26 - October 20, 2016 */
+/* Libpng version 1.6.27 - December 29, 2016 */
 
 /* Copyright (c) 1998-2015 Glenn Randers-Pehrson */
 
diff --git a/scripts/symbols.def b/scripts/symbols.def
index 612d211..d04f095 100644
--- a/scripts/symbols.def
+++ b/scripts/symbols.def
@@ -1,4 +1,4 @@
-;Version 1.6.26
+;Version 1.6.27
 ;--------------------------------------------------------------
 ; LIBPNG symbol list as a Win32 DEF file
 ; Contains all the symbols that can be exported from libpng