The code no longer gives up/fails on invalid PNG data, it just skips it (with
error messages).  The code no longer fails on PNG files with data beyond IEND.
Options exist to use png_read_png (reading the whole image, not by row) and, in
that case, to apply any of the supported transforms.  This makes for more
realistic testing; the decoded data actually gets used in a meaningful fashion.
Signed-off-by: NJohn Bowler <jbowler@acm.org>

and added PNG_NO_INTEL_SSE_3BPP macro.

their new location in contrib/intel/* (was intel/*)

necessarily under the libpng license, and that some makefiles have
other copyright owners.

libpng-1.6.19bet02 (John Bowler).

(Robert C. Seacord).

were accidentally removed from libpng-1.6.17.

to the LICENSE file, png.h, and the man page.

As suggested in the comments gamma values outside the range currently permitted
by png_set_alpha_mode are useful for HDR data encoding.  These values are
already permitted by png_set_gamma so it is reasonable caution to extend the
png_set_alpha_mode range as HDR imaging systems are starting to emerge.
Signed-off-by: NJohn Bowler <jbowler@acm.org>

Also avoid command output substition in tests/pngstest and fix the collation
locale to ASCII/C/POSIX
Signed-off-by: NJohn Bowler <jbowler@acm.org>

and test.cmake.in

The macro underreported the size (by up to 512 bytes) of an 8-bit non-color
palette based memory format because it failed to take into account that the
memory palette has to be expanded to full RGB when it is written to PNG.

This is not likely to be a serious bug because the macro is new, the memory
format in question is likely to be rarely used and the result of an undersized
buffer fails in a safe way.
Signed-off-by: NJohn Bowler <jbowler@acm.org>