I've come across this issue on occasion as well, and would be
interested in a fix. Next time it occurs I'll retrieve the document and
see what I can learn about it. Unfortunately I will probably not be able
to share it.
Cory
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On
> Behalf Of Tessler, Micah (M.B.)
> Sent: Tuesday, May 06, 2008 12:00 PM
> To: Post all your questions about iText here
> Subject: Re: [iText-questions] Invalid TIFF -- Invalid
> codeencounteredwhiledecoding 2D group 4 compressed data.
>
> Thanks for the response, but I remain skeptical that large
> numbers of scanners are corrupting the T6 compression
> standard. And all of the commercial tiff readers (I haven't
> tried open-source readers other than iText) understand this
> corruption.
>
> I submit that a more logical interpretation of the evidence
> is that there is another standard, other than official T6,
> that these systems are coded to. While the TIFF tag says the
> file is T6 compressed, the compression appears to adhere to
> an extension of the standard. I would be curious if anyone
> has come across these expanded/updated standards.
>
> Questions:
> 1) Has anyone else come across these expanded/updated standards?
>
> 2) Has anyone found an open-source tiff-viewer that can
> handle these corrupted tiffs? If so, iText may be able to
> share the expanded decoding algorithm with said viewer.
>
> Micah Tessler
> Consulting Architect
> Ford Credit Enterprise Architecture
> (313) 322-4267
> [EMAIL PROTECTED]
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On
> Behalf Of Paulo Soares
> Sent: Monday, May 05, 2008 1:02 PM
> To: Post all your questions about iText here
> Subject: Re: [iText-questions] Invalid TIFF -- Invalid code
> encounteredwhiledecoding 2D group 4 compressed data.
>
> Please post your fix. Apparentely nobody can produce correct
> G4 files and the burden is on the viewers to fix the broken
> files. iText does some effort to fix it but only goes so far.
>
> Paulo
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED] On Behalf Of
> > Tessler, Micah (M.B.)
> > Sent: Monday, May 05, 2008 5:20 PM
> > To: [email protected]
> > Subject: [iText-questions] Invalid TIFF -- Invalid code encountered
> > whiledecoding 2D group 4 compressed data.
> >
> > I am working with a set of tiffs, several of which are invalid.
> > When reading into iText, I get the following error message:
> > Invalid TIFF -- Invalid code encountered while decoding 2D group 4
> > compressed data.
> > iText version = 2.02
> >
> > My question is regarding the cause of the issue and some possible
> > approaches to fixing it.
> >
> > Windows Picture and Fax Viewer, and Microsoft Paint can
> both read and
> > render the invalid tiffs, but iText always errors out.
> >
> > In the iText code, I was able to fix the error by modifying
> the iText
> > method:
> > com.lowagie.text.pdf.codec.TIFFFaxDecoder.decodeT6()
> >
> > Where there is an if/else block within a loop that checks
> the code to
> > decide if something is horizontal (code=1), vertical (codes = 2-8),
> > pass (code=0), or extension (code = 11), I am getting a code of 10.
> >
> > iText libraries throw the exception "Invalid TIFF -- Invalid code
> > encountered while decoding 2D group 4 compressed data."
> > in that case. I hacked the code to instead do the following in the
> > unknown code block to treat the invalid code as a
> line-break. Which
> > renders the Tiff in iText the same way that the as the Microsoft
> > viewers do.
> >
> > bitOffset = w;
> > updatePointer(7 - bits);
> >
> > Questions:
> > 1) Is the 10-code linebreak a valid extension to the T-6 spec?
> > 2) How would one go about "fixing" the tiff data to be
> iText friendly?
> > Removing the bad codes and inserting enough
> horizontal white
> > pixels to end the line?
> > 3) Is there a later release of iText that addresses the
> invalid tiff
> > question?
> >
> > Thanks,
> > -Micah
> >
> >
> > Micah Tessler
> > Consulting Architect
> > Ford Credit Enterprise Architecture
> > (313) 322-4267
> > [EMAIL PROTECTED]
> >
> >
>
>
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