[pdf-devel] JBIG2: torture/testdata/TD0000* and jbig2dec

[Georg Gottleuber]

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Hello,

maybe someone else is working on JBIG2 support. If so this information
might be useful to him/her.

1.) The test data for JBIG2 (torture/testdata/TD0000*) is not correct.
With some search I found the source of the TD0000* files: It is the
second page of this document:
(http://www.circuitwizard.de/pdftex/old-jbig2/foo.pdf)

The TD00003 file is claimed as the result of decoding TD00001 and
TD00002, but if you attach the BPM header it shows an empty box.
Acroread and poppler are showing a JBIG2 halftone gradient.

I extracted the decoded bitmap from poppler (with pdfimages) and checked
the halftones against a screenshot from Adobe Reader. It's the same
bitmap.

Attached you find a patch with the correct TD00003 file.

2.) Even if you compile jbig2dec-0.11 for yourself with -DJBIG2_HALFTONE
enabled, the output of jbig2dec is with an empty box (without the
halftones). So the problem about halftones is not caused by the GNU PDF
code. This will cause a permanent failure of the unit test I am going to
create, until jbig2dec is able to handle halftone.

3.) I was confused by torture/testdata/TD0000*.desc that makes
statements about the global segment (singular). Later I found out, that
TD00001 contains 2 global segments. Therefore I changed the description
files to plural. (Of course it is a small thing, but it cost me hours of
debugging.)

Regards,
Georg
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testdata_patch
Description: Text document