RE: 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
> > 
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