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Re: [hylafax-users] Receiving a color fax



Hello Lee

Lee Howard wrote:

Blas Rodriguez Somoza wrote:

In the RFC2301 (chapter 6.2.1) there is very clear reference to the encoding used in faxes :

PhotometricInterpretation(262) = 10. SHORT Base color fax mode requires pixel values to be stored using the CIE L*a*b* encoding defined in ITU-T Rec. T.42. This encoding is indicated by the PhotometricInterpretation value 10, referred to as ITULAB

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.

Thanks,

Lee.

Regards Blas


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