Re: [hylafax-users] Receiving a color fax

[Blas Rodriguez Somoza <blas@xxxxxxxxxxxxx>]

Hello Lee

Blas Rodriguez Somoza wrote:

> Hello Lee
>
> Lee Howard wrote:
>
> > Okay, so I'm with you on this now.  The PhotometricInterpretation 
> > TIFF tag for color faxes needs to be ITULAB (10).  Making that change 
> > in HylaFAX will be very easy to do, but once that's done then we end 
> > up with no way to use that TIFF image file... because nothing out 
> > there can utilize that encoding type.  So we'd have to make come 
> > corrections or modifications to libtiff.  It would *seem* that at 
> > least tiff2ps (via patched libjpeg) is doing things correctly... 
> > except that it, too, internally refers to the wrong name for the 
> > encoding.  Is it just a matter of renaming things?  In any case once 
> > we start looking at working on code in libtiff I get hesitant, and I 
> > simply do not know what I'm doing in libjpeg.  The problem being, 
> > however, that because ITULAB is fax-specific there just aren't many 
> > libjpeg developers that are interested. 
>
> OK
>
> > Are you at all in position where you'd like to work on some code in 
> > libjpeg and libtiff?
> I'm working on it.
>
> I get tiffcp working for the ITULab -> RGB conversion.
>
> I'm trying now to allow also tiffcp RGB->ITULab & RGB->YCbCr conversions.
>
> I'll send the new patches as soon as I finish it.
   Finally I get all the jpeg colorspace conversions from [Minisblack | 
RGB | YCbCr | ITULAB] to [Minisblack | RGB | YCbCr | ITULAB]  working in 
tiffcp.

   So with the changes is possible to convert from ITULAB to RGB, YCbCr 
or Grayscale with good results.

   Also I found and solve two bugs in the patch to jpeg. These bugs 
only appear when reading more than one page.

   I expend a lot of time with gdb and I can't find the problem, until 
I use Valgrind and I find and solve it in 5 minutes !!
  
   I packed the resulting sources in two source rpm based on 
libjpeg-6b-34 and tiff-3.8.0.



Regards
Blas

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