Re: Fix for Bug 686980, stripes in pdf.

Jeong,

I've meant something like you wrote, but this is only my opinion.
Architectural decision to be taken by Raph.

Igor.

----- Original Message ----- 
From: "Jeong Kim" <[email protected]>
To: "'Igor V. Melichev'" <[email protected]>; "'gs-code-review'"
<[email protected]>
Sent: Saturday, August 16, 2003 4:43 PM
Subject: RE: [gs-code-review] Fix for Bug 686980, stripes in pdf.


> Igor,
>
> Are you meaning that I should make a new code file to substitute
> 'jdmarker.c' just like the way 'gsjmorec.h' substitutes 'jmorecfg.h'?
> Or are you meaning something else?
>
> Jeong
>
> > -----Original Message-----
> > From: [email protected]
> > [mailto:[email protected]] On Behalf Of
> > Igor V. Melichev
> > Sent: Wednesday, August 13, 2003 12:37 AM
> > To: Jeong Kim; 'gs-code-review'
> > Subject: Re: [gs-code-review] Fix for Bug 686980, stripes in pdf.
> >
> >
> > A possible resolution is to call the patch utility from GS makefiles.
> >
> > Igor.
> >
> > ----- Original Message ----- 
> > From: "Jeong Kim" <[email protected]>
> > To: "'gs-code-review'" <[email protected]>
> > Sent: Tuesday, August 12, 2003 4:11 PM
> > Subject: [gs-code-review] Fix for Bug 686980, stripes in pdf.
> >
> >
> > > Reviewers,
> > >
> > > In the given sample file, some parts of the pictures are using
> > > DCTDecode filter with DeviceCMYK color space, but component
> > id values
> > > in the stream data are not unique for each color channels.
> > Again, they
> > > use same id values
> > > (1) for both cyan and black channel.
> > >
> > > This makes a serious conflict and then jpeg decoder
> > over-writes data
> > > for black channel onto cyan channel for this reason.
> > Therefore, output
> > > cyan channel has
> > > data for black and black channel has dummy data.
> > >
> > > That's why we have noisy black output and cyan images
> > instead of black
> > > ones.
> > >
> > > These problems are due to incorrect input data not to
> > Ghostscript or
> > > jpeg library. But Adobe Acrobat reads this file corretly.
> > So I did a
> > > clumsy hack on jpeg library.
> > >
> > > In jpeg/jdmarker.c
> > >
> > > 282:    INPUT_BYTE(cinfo, compptr->component_id, return FALSE);
> > > compptr->component_id = ci+1; <---
> > >
> > > 327:    INPUT_BYTE(cinfo, cc, return FALSE);
> > >     cc = i+1; <---
> > >
> > > I inserted two arrow-marked lines. Now jpeg library ignores the
> > > component id values from input stream. It just generates ids
> > > sequentially.
> > >
> > > Now everything is OK. But I think modifying jpeg library instead of
> > > Ghostscript could be problematic. Any advice or comment on
> > this issue
> > > is welcome.
> > >
> > > Jeong
> > >
> > > _______________________________________________
> > > gs-code-review mailing list
> > > [email protected]
> > > http://www.ghostscript.com/mailman/listinfo/gs-code-review
> > >
> > _______________________________________________
> > gs-code-review mailing list
> > [email protected]
> > http://www.ghostscript.com/mailman/listinfo/gs-code-review
> >
>
>