libpng-1.6.9, 1.5.18, 1.4.13, 1.2.51, and 1.0.61 are available from
ftp://ftp.simplesystems.org/pub/png/src
and from
http://libpng.sf.net

version 1.0.61 and 1.2.51 [February 6, 2014]
  Ignore, with a warning, out-of-range value of num_trans in png_set_tRNS().
  Replaced AM_CONFIG_HEADER(config.h) with       AC_CONFIG_HEADERS([config.h]) in configure.ac
  Changed default value of PNG_USER_CACHE_MAX from 0 to 32767 in pngconf.h.
  Avoid a possible memory leak in contrib/gregbook/readpng.c
  Revised libpng.3 so that "doclifter" can process it.
  Changed '"%s"m' to '"%s" m' in png_debug macros to improve portability
    among compilers.
  Rebuilt the configure scripts with autoconf-2.69 and automake-1.14.1
  Removed potentially misleading warning from png_check_IHDR().
  Quiet set-but-not-used warnings in pngset.c
  Quiet an uninitialized memory warning from VC2013 in png_get_png().
  Quiet unused variable warnings from clang by porting PNG_UNUSED() from
    libpng-1.4.6.
  Added -DZ_SOLO to CFLAGS in contrib/pngminim/*/makefile
  Added an #ifdef PNG_FIXED_POINT_SUPPORTED/#endif in pngset.c

version 1.4.13 [February 6, 2014]
  Do not compile PNG_DEPRECATED, PNG_ALLOC and PNG_PRIVATE when __GNUC__ < 3.
  Removed references to png_zalloc() and png_zfree() from the manual.
  Ignore, with a warning, out-of-range value of num_trans in png_set_tRNS().
  Replaced AM_CONFIG_HEADER(config.h) with AC_CONFIG_HEADERS([config.h])
    in configure.ac
  Changed default value of PNG_USER_CACHE_MAX from 0 to 32767 in pngconf.h.
  Avoid a possible memory leak in contrib/gregbook/readpng.c
  Removed a redundant test from png_set_IHDR().
  Revised libpng.3 so that "doclifter" can process it.
  Changed '"%s"m' to '"%s" m' in png_debug macros to improve portability
    among compilers.
  Rebuilt the configure scripts with autoconf-2.69 and automake-1.14.1
  Removed potentially misleading warning from png_check_IHDR().
  Quiet set-but-not-used warnings in pngset.c
  Quiet an uninitialized memory warning from VC2013 in png_get_png().

version 1.5.18 [February 6, 2014]
  Delay calling png_init_filter_functions() until a row with nonzero filter
    is found.
  Changed tabs to 3 spaces in png_debug macros and changed '"%s"m'
    to '"%s" m' to improve portability among compilers.
  Added "-Wall" to CFLAGS in contrib/pngminim/*/makefile
  Conditionally compile some unused functions reported by -Wall in
    pngminim.
  Rebuilt configure scripts with automake-1.14.1 and autoconf-2.69
    in the tar distributions.
  Fixed 'unused' warnings and merged with libpng16 pngvalid.
    Various warnings revealed by configurations added to the tested
    configurations in libpng 1.6 need corresponding fixes in libpng 1.5.
    This takes the libpng 1.6 pngvalid.c and adds it back to libpng 1.5,
    however one write-only test is currently disabled because it does not
    work; possibly because of failures to reset or initialize the deflate
    stream correctly in write-only cases.
  Merged libpng-1.7 changes and created a single pngvalid.c
  Merged pngvalid and pngtest from libpng-1.5; made compressed chunks
    after IDAT work with the progressive read code (this is a minor and
    somewhat ugly fix-up; the proper fix is in 1.6).
  The 'make all-am' command no longer builds $(check_PROGRAMS), leading
    to a lack of checks on cross-builds such as ARM.  Makefile.am also
    requires correct dependencies for the check programs on pnglibconf.h
    otherwise parallel builds on fast machines can sometimes pick up the
    system pnglibconf.h.
  Rebuilt configure scripts with automake 1.14.1 and autoconf-2.69.
  Require automake-1.13 and enable automake "subdirs" feature in autoconf.ac.
  Allow unversioned links created on install to be disabled in configure.
    In configure builds 'make install' changes/adds links like png.h
    and libpng.a to point to the newly installed, versioned, files (e.g.
    libpng17/png.h and libpng17.a). Three new configure options and some
    rearrangement of Makefile.am allow creation of these links to be disabled.
  Removed potentially misleading warning from png_check_IHDR().
  Updated scripts/makefile.* to use CPPFLAGS (Cosmin)
  Quiet an uninitialized memory warning from VC2013 in png_get_png().

version 1.6.9 [February 6, 2014]
  Bookkeeping: Moved functions around (no changes). Moved transform
    function definitions before the place where they are called so that
    they can be masde static. Move the intrapixel functions and the
    grayscale palette builder out of the png?tran.c files. The latter
    isn't a transform function and is no longer used internally, and the
    former MNG specific functions are better placed in pngread/pngwrite.c
  Made transform implementation functions static. This makes the internal
    functions called by png_do_{read|write}_transformations static. On an
    x86-64 DLL build (Gentoo Linux) this reduces the size of the text
    segment of the DLL by 1208 bytes, about 0.6%. It also simplifies
    maintenance by removing the declarations from pngpriv.h and allowing
    easier changes to the internal interfaces.
  Rebuilt configure scripts with automake-1.14.1 and autoconf-2.69
    in the tar distributions.
  Added checks for libpng 1.5 to pngvalid.c.  This supports the use of
    this version of pngvalid in libpng 1.5
  Merged with pngvalid.c from libpng-1.7 changes to create a single pngvalid.c
  Removed #error macro from contrib/tools/pngfix.c (Thomas Klausner).
  Merged pngrio.c, pngtrans.c, pngwio.c, and pngerror.c with libpng-1.7.0
  Merged libpng-1.7.0 changes to make no-interlace configurations work
    with test programs.
  Revised pngvalid.c to support libpng 1.5, which does not support the
    PNG_MAXIMUM_INFLATE_WINDOW option, so #define it out when appropriate in pngvalid.c
  Allow unversioned links created on install to be disabled in configure.
    In configure builds 'make install' changes/adds links like png.h
    and libpng.a to point to the newly installed, versioned, files (e.g.
    libpng17/png.h and libpng17.a). Three new configure options and some
    rearrangement of Makefile.am allow creation of these links to be disabled.
  Removed potentially misleading warning from png_check_IHDR().
  Updated scripts/makefile.* to use CPPFLAGS (Cosmin).
  Added clang attribute support (Cosmin).
  Quiet an uninitialized memory warning from VC2013 in png_get_png().

In all releases I relocated the Gpg signatures from a Gnupg subdirectory
to the more conventional location alongside the distribution files.

Glenn R-P