Fixes for sBIT handling in the low-bit-depth gray and pngstest cases, extends
sBIT handling to the colormap code in the simplified API which is separately
implemented in pngread.c
Signed-off-by: John Bowler <jbowler@acm.org>
commit bf51c644f7d29400d884e20def9a0bee74904308
Author: John Bowler <jbowler@acm.org>
Date: Tue Sep 22 09:05:13 2015 -0700
Updated contrib/testpngs/*.png
Corrected copyright/licensing information, corrected filtering.
Signed-off-by: John Bowler <jbowler@acm.org>
commit 05399c8c82d7b188357dc6fa05a8cdd89426b155
Author: John Bowler <jbowler@acm.org>
Date: Tue Sep 22 09:04:03 2015 -0700
makepng.c: correct the first row filter setting
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>
commit 8fae6609c063c7e0a5eeb592f8eec15849617ae9
Author: John Bowler <jbowler@acm.org>
Date: Mon Sep 21 17:15:45 2015 -0700
makepng: spelling corrections, single test output
Corrections to some obvious mistakes, plus one output file.
Signed-off-by: John Bowler <jbowler@acm.org>
commit a2245a2c54a679d25f8f1609f85654d155936863
Author: John Bowler <jbowler@acm.org>
Date: Mon Sep 21 13:39:48 2015 -0700
Updated testpngs files with new Licensing tag
Signed-off-by: John Bowler <jbowler@acm.org>
commit 46d3f863cace5b7aa769c9b882fca49e2a821138
Author: John Bowler <jbowler@acm.org>
Date: Mon Sep 21 13:38:34 2015 -0700
Updated makepng.c
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>
commit 7c9a08b8bc5e2542184d4abb25c33c516bc0adc7
Author: John Bowler <jbowler@acm.org>
Date: Sun Sep 20 20:55:19 2015 -0700
Test PNG files
These files were generated by contrib/testpngs/makepngs.sh --small with MAKEPNG
set to the makepng compiled from the current contrib/libtests/makepngs.sh
Signed-off-by: John Bowler <jbowler@acm.org>
commit c2a8a01b2ac733b8029478d10f700f5ab8a713f2
Author: John Bowler <jbowler@acm.org>
Date: Sun Sep 20 20:51:06 2015 -0700
makepng --small
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>
commit 8c025bcf3fdfb68fb8b1e5fab4b7deb0f94453f6
Author: John Bowler <jbowler@acm.org>
Date: Sun Sep 20 20:40:52 2015 -0700
Simplified API sRGB gamma handling correction
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>
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>
a flag to change default. In 1.6.0 when the simplified API was used
to produce color-mapped output from an input image with no gamma
information the gamma assumed for the input could be different from
that assumed for non-color-mapped output. In particular 16-bit depth
input files were assumed to be sRGB encoded, whereas in the 'direct'
case they were assumed to have linear data. This was an error. The
fix makes the simplified API treat all input files the same way and
adds a new flag to the png_image::flags member to allow the
application/user to specify that 16-bit files contain sRGB data
rather than the default linear.
Fixed bugs in the pngpixel and makepng test programs.
option to pngtest. The "--relaxed" option turns off the benign errors that are
enabled by default in pre-RC builds. makepng can now write ICC profiles
where the length has not been extended to a multiple of 4, and pngtest
now intercepts all libpng errors, allowing the previously-introduced
"--strict test" on no warnings to actually work.
contrib/libtests/makepng: corrected 'rgb' and 'gray' cases. profile_error
messages could be truncated; made a correct buffer size calculation and
adjusted pngerror.c appropriately. png_icc_check_* checking improved;
changed the functions to receive the correct color type of the PNG on read
or write and check that it matches the color space of the profile (despite
what the comments said before, there is danger in assuming the app will
cope correctly with an RGB profile on a grayscale image and, since it
violates the PNG spec, allowing it is certain to produce inconsistent
app behavior and might even cause app crashes.) Check that profiles
contain the tags needed to process the PNG (tags all required by the ICC
spec). Removed unused PNG_STATIC from pngpriv.h.
all potentially valid ICC profiles and reject obviously invalid ones.
It now uses png_error() to do so rather than casually writing a PNG
without the necessary color data.
generator. The generator generates images that test the full range of sample
values, allow the error numbers in pngstest to be tuned and checked. makepng
also allows generation of images with extra chunks, although this is
still work-in-progress.
