It needs to include the "UP" filter so that libpng knows to retain the first
line for the UP filter on the next one. Without this libpng ended up using NONE
for the second line.
Signed-off-by: John Bowler <jbowler@acm.org>
This supports more test cases and a reduced licence keyword (now licensing).
The extra text cases require more slack in pngstest.c
Signed-off-by: John Bowler <jbowler@acm.org>
This patch adds code to 'makepng' to allow the generation of smaller images that
also give better test case coverage. It also adds copyright and licence to the
generated images, reflecting the fact that they are original works of the author
of the code. The licence used is the Creative Commons Public Domain one,
appropriate to a non-source-code work.
The resultant image were used to generate the updated pngstest-errors.h file in
a prior commit.
Signed-off-by: John Bowler <jbowler@acm.org>
If a gamma encoded file that has a gamma not matching that of sRGB is passed to
the simplified API the previous code simply interpreted it as a power law
encoding. However old Mac files had a power law correction of 1.45 built in to
the encoding, even though the display devices were consistent with sRGB.
Assuming a power law encoding results in substantial differences in the
interpretation of low 8-bit values; below 10. For example an Apple '5' which is
equivalent to an sRGB '17' ends up as the value '8'.
This patch provides some measure of correction for this by making the gamma
correction done within the simplified API assume that any encoded data is
encoded relative to an sRGB-like transfer function; the data is corrected back
to the PNG-nominal 2.2 value then decoded to linear (if required) using the sRGB
transfer function.
This reduces the errors reported by pngstest for such files (colormapped ones)
but still leaves the issue with files where the standard libpng code does the
gamma decoding. To cope with the latter cases the patch also includes a new
pngstest-errors which allows the result, however this is still a
work-in-progress; a better solution is possible.
Signed-off-by: John Bowler <jbowler@acm.org>
Splitting the machine generated error structs out to a file allows the values to
be updated without changing pngstest.c itself, sine libpng 1.6 and 1.7 have
slightly different error limits this simplifies maintenance.
makepngs.sh has also been updated to more accurately reflect current problems in
libpng 1.7
Signed-off-by: John Bowler <jbowler@acm.org>
The low-bit-depth gray tests were disabled in prior versions of libpng because
of problems which should have been fixed by the recent changes to libpng17,
enabling the tests reveals bugs in those changes which are fixed by this commit.
Signed-off-by: John Bowler <jbowler@acm.org>
Most of these are back-portable to earlier versions (contrib/libtests
should just work with earlier versions), however the 1.7 specific
changes in pngvalid mean that it probably won't work against 1.7 without
the commits following this one.
Signed-off-by: John Bowler <jbowler@acm.org>
handling in contrib/libtests/pngstest.c; possible overflow of
unsigned char in contrib/tools/png-fix-itxt.c). To use the "secure"
file handling, define PNG_USE_MKSTEMP, otherwise "tmpfile()" will
be used.
pngstest.c, and pngimage.c. Most seem harmless, but png-fix-itxt
would only work with iTXt chunks with length 255 or less.
Fixed cexcept.h in which GCC 5 reported that one of the auto
variables in the Try macro needs to be volatile to prevent value
being lost over the setjmp, and fixed g++ build breaks (John Bowler).
internal struct (png_transform_control) to replace row_info and uses
that to implement affirms correctly. The change also adds checks on
the rowbytes calculation and additional checks on most transform
implementations.
Added png_uint_16 range checking, pngvalid tRNS, fixed png_uint_16:
review of previous checks, removal of some where SAFE. pngvalid: add
testing of tRNS for better code coverage pngvalid: correct rgb-to-gray
error calculations. Code coverage is still incomplete: see /*UNTESTED*/
in pngrtran.c
seem to generate warnings when an unsigned value is implicitly
converted to double. This is probably a GCC bug but this change
avoids the issue by explicitly converting to (int) where safe.
Free all allocated memory in pngimage. The file buffer cache was left
allocated at the end of the program, harmless but it causes memory
leak reports from clang.
Fixed array size calculations to avoid warnings. At various points
in the code the number of elements in an array is calculated using
sizeof. This generates a compile time constant of type (size_t) which
is then typically assigned to an (unsigned int) or (int). Some versions
of GCC on 64-bit systems warn about the apparent narrowing, even though
the same compiler does apparently generate the correct, in-range,
numeric constant. This adds appropriate, safe, casts to make the
warnings go away.
scripts. Fixed combination of ~alpha with shift. On read invert alpha,
processing occurred after shift processing, which causes the final values to be
outside the range that should be produced by the shift. Reversing the
order on read makes the two transforms work together correctly and mirrors
the order used on write.
This is a work-in-progress; no tests are run automatically at present and
the program by virtue of exhaustively testing all the transforms is
very slow.
Fixed 'minimal' builds. Various obviously useful minimal configurations
don't build because of missing contrib/libtests test programs and overly
complex dependencies in scripts/pnglibconf.dfa. This change adds
contrib/conftest/*.dfa files that can be used in automatic build
scripts to ensure that these configurations continue to build.
Enabled WRITE_INVERT and WRITE_PACK in contrib/pngminim/encoder.
the useful side effect of avoiding a bogus warning generated by the latest
version of the Intel C compiler (it objects to
condition ? string-literal : string-literal).
