GoogleCodeExporter
commented
8 years ago Thank you for the detailed bug report. Based on the files
image_optimze_error.txt and Pages1-7.psom.pdf you have uploaded I could figure
what's going wrong. I'm almost sure that I've identitied an easy-to-fix bug in
your jbig2.exe. Once you fix the bug, recompile jbig2.exe, and rerun
pdfsizeopt, it will be fine.
On Windows it's possible to open files in either ASCII or binary mode. ASCII is
the default; you can have binary by passing ...|O_BINARY to the 2nd argument of
open(), or passing a string containing "b" (e.g. "rb" instead of "r"; "wb"
instead of "w") to the 2nd argument of fopen(), or calling setmode(1, O_BINARY)
to put stdout to binary mode. If a file is opened in ASCII mode, than all
writes (e.g. write(...), putchar(...), fwrite(...), fprintf(...)) of "\n" (10)
actually write "\r\n" (13, 10) to the file.
In our case, jbig2.exe writes the JBIG2-compressed image to its stdout, e.g.
see the line
info: executing image optimizer jbig2: jbig2 -p pso.conv-3.sam2p-pr.png
>pso.conv-3.jbig2
in the image_optimze_error.txt you have uploaded. The bug is that jbig2.exe
writes to stdout in ASCII mode, but binary mode would be correct. It's easy to
fix: please add setmode(1, O_BINARY) to the beginning of the main() function of
jbig2.exe , recomplie jbig2.exe, and rerun the optimization like this:
$ pdfsizeopt.py --use-pngout=no Pages1-7.pdf
Now Pages1-7.psom.pdf should be correct, and the JBIG2 file should be a few
bytes shorter, as indicated on the console output. Old, incorrect:
info: optimized image XObject 3 file_name=pso.conv-3.jbig2 size=2109 (58%)
methods=jbig2:2109,#orig:3637,pngout:6793,sam2p_np:7011,sam2p_pr:8586,gs:11056
New, correct:
info: optimized image XObject 3 file_name=pso.conv-3.jbig2 size=2102 (58%)
methods=jbig2:2102,#orig:3637,sam2p_np:7011,sam2p_pr:8586,gs:11050
(Please note the difference between 2019 and 2012 bytes.)
If this O_BINARY change doesn't fix the problem, then please upload the entire
directory (containing the pso.* temporary files) ZIPped as an attachment to
this issue. Also include the recompiled jbig2.exe you use, and the console
output of pdfsizeopt.
To illustrate my point, I've modified a few bytes of Pages-1.7.psop.pdf : I've
removed the 7 extra \r characters (and added some padding after the obj the
make the file size the same). This effectively fixed the image of page 2. So if
you make jbig2.exe not emit the \r characters, most probably the whole PDF
would be fixed.
If you manage to fix jbig2.exe, please upload it as an attachment to this
issue, so others would also benefit.Original comment by pts...@gmail.com on 26 Jun 2012 at 9:10
Attachments:
Original issue reported on code.google.com by
fdnc...@gmail.comon 26 Jun 2012 at 1:03Attachments: