[gs-bugs] [Bug 698727] - Ghostscript - Possible problem with CCITT Group 3 Fax Encoding

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698727

Bug ID: 698727
Summary: Possible problem with CCITT Group 3 Fax Encoding
Product: Ghostscript
Version: master
Hardware: PC
OS: Windows 7
Status: UNCONFIRMED
Severity: normal
Priority: P4
Component: General
Assignee: ghostpdl-***@artifex.com
Reporter: ***@artifex.com
QA Contact: gs-***@ghostscript.com
Word Size: ---

Created attachment 14445
--> http://bugs.ghostscript.com/attachment.cgi?id=14445&action=edit
test file

The customer states that, when using superfine Fax resolution (408x391), the
file produced by the faxg3 device cannot be read by their software.

Using the PostScript CCITTFaxDecode filter, I can read the output of faxg3 at
the default resolution, setting the resolution to -r408x391 produces a file
which the CCITTFaxDecode filter throws an ioerror on.

Its possible the faxg3 device simply isn't capable of producing superfine fax
output, its not obvious to me, but it looks like it should be OK from a quick
glance.

It is also possible that the output is correct, and the Decode filter is
broken, or possibly everything is correct and I'm just misunderstanding the
issue.

Attached file is from the customer, but I don't believe its confidential in any
way.

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698727

Ken Sharp <***@artifex.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
Customer| |999999
Assignee|ghostpdl-***@artifex.com |***@artifex.com

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698727

Ken Sharp <***@artifex.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
Customer|999999 |665

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698727

Henry Stiles <***@artifex.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
CC| |***@artifex.com
Priority|P4 |P2

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698727

Robin Watts <***@artifex.com> changed:

What |Removed |Added
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CC| |***@artifex.com

--- Comment #1 from Robin Watts <***@artifex.com> ---
Not speaking postscript as well as Ken, I took the output from:

gs -sDEVICE=faxg3 -r408x391 -o out.fax

and pickled it into a PDF file.

My first attempt at this produced a PDF file where the filter was indeed
complaining. After I debugged through the decode in gs, I noted that the filter
was starting with Columns set to the default value of 1728.

I then tweaked the file to set /DecodeParms << /Columns 3468 >> and it started
to work fine in gs, MuPDF and Acrobat.

Therefore, I believe our faxg3 output is perfectly formed. I suspect their
input software may similarly be assuming the default maximum linewidth too.

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698727

--- Comment #2 from Robin Watts <***@artifex.com> ---
Created attachment 14452
--> http://bugs.ghostscript.com/attachment.cgi?id=14452&action=edit
fax2.pdf

Example file as referenced in comment #2.

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698727

Robin Watts <***@artifex.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |WORKSFORME
Status|UNCONFIRMED |RESOLVED

--- Comment #3 from Robin Watts <***@artifex.com> ---
Closing as Ghostscript appears to be working as expected.

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698727

Ken Sharp <***@artifex.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |NOTIFIED