Bug 690791

Summary:	Random noise reading PDF file
Product:	Ghostscript	Reporter:	Marcos H. Woehrmann <marcos.woehrmann>
Component:	Images	Assignee:	Ralph Giles <ralph.giles>
Status:	NOTIFIED FIXED
Severity:	normal	CC:	drugo.pedrouvene
Priority:	P2	Keywords:	bountiable
Version:	master
Hardware:	All
OS:	All
Customer:	170	Word Size:	---
Attachments:	Bug690791.diff

Description Marcos H. Woehrmann 2009-09-29 20:51:02 UTC

The customer reports and I've verified that instead of the expected output the attached PDF file 
produces random noise when read by Ghostscript.  gs8.64, gs8.70, and head (r10102) all behave the 
same way.

The command line I'm using for testing:

  bin/gs -sDEVICE=tiff24nc -o test.tif ./OriginalFile.pdf

Note that this is an OCR'd PDF file, consisting of a page of text with an image on top.  The problem 
appears to be with Ghostscript reading the image; if instead of TIFF you convert the attached file to PDF 
and then view it in Acrobat you can see the OCR'd text being drawn before being overlaid with the 
random noise image.

Comment 1 Marcos H. Woehrmann 2009-09-29 20:51:46 UTC

Created attachment 5413 [details]
OriginalFile.pdf

Comment 2 Alex Cherepanov 2009-10-05 20:39:39 UTC

Created attachment 5449 [details]
a8-2i4.pdf

Simplified sample file that has only JBIG2 image.

Comment 3 Ray Johnston 2009-10-28 09:25:59 UTC

Customer reports that this is a critical issue for them.

Comment 4 Ralph Giles 2009-10-29 02:52:25 UTC

Just an update. We appear to be decoding the symbol dictionary and text region
correctly, but not the final generic region. Disabling the fourth segment gives
proper results.

Comment 5 Ralph Giles 2009-11-20 10:15:56 UTC

The problem is the file includes a refinement region with typical prediction,
which we haven't implemented. Resolution of the bug just requires doing so.

In the meantime, I've committed a work-around patch to skip the refinement data
when we can't decode it as r10362. With this patch, rendering is not completely
correct, but is much better as it removes the obscuring layer of noise.

Comment 6 Ralph Giles 2009-11-23 17:35:49 UTC

*** Bug 690913 has been marked as a duplicate of this bug. ***

Comment 7 Ralph Giles 2009-11-23 21:41:31 UTC

Created attachment 5705 [details]
Bug690791.diff

Attaching a backport patch against 8.64/8.70 which fixes the problem.

Comment 8 Marcos H. Woehrmann 2011-09-18 21:47:25 UTC

Changing customer bugs that have been resolved more than a year ago to closed.