[tex-live] ICC profiles for PDF/A compliance

[Reinhard Kotucha]

On 2018-09-07 at 10:34:23 +0900, Norbert Preining wrote:

 > Interesting. They seem to have a big mess up there ;-)

Yes, but maybe I can provide more information.

First of all, the pdfx package was formerly maintained by Thành and
Radhakrishnan at Sarovar.  There was a web page with HTML
documentation and a file "sRGBIEC1966-2.1.icm".  See attachment.

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At this time I was working on a PDF/A implementation in LuaTeX for a
commercial product.  I couldn't use this profile because there was no
explicit license, only a string within the file

  "Copyright (c) 1998 Hewlett-Packard Company" 

Thus I looked for a better one and found
"sRGB_IEC61966-2-1_black_scaled.icc" at color.org.  The license was
not only good for my project, it was good for FSF, Debian, and TeX
Live as well.  So I asked Ross, the new maintainer of pdfx, to replace 
"sRGBIEC1966-2.1.icm" by "sRGB_IEC61966-2-1_black_scaled.icc".

What I didn't know until yesterday:  Debian guys found out that
there were two conflicting licenses.  One allows and one forbids
modification.  They asked the ICC for clarification and the answer
was not delightful.  As a result, the ICC changed the license
statement on their web site.

Below is the PostScript code shipped with Ghostscript
("Resource/ColorSpace/sRGB").  It contains the line

   % sRGB color space derived from the public domain HP sample.

which makes me believe that it's derived from the same file
"sRGBIEC1966-2.1.icm" Thành formerly maintained at Sarovar.

Presumably HP shipped this file on CDs accompanied by their printers
without further licensing information.

The data in the file below is freely available, see

  https://en.wikipedia.org/wiki/SRGB

So if we don't find an ICC sRGB profile with an appropriate license we
can create one ourselves with a license which makes everybody happy.
All we need is a specification of the .icc binary format.

For the time being, Norbert, could you add the file

  sRGB_IEC61966-2-1_black_scaled.icc

to tlcontrib if you haven't done this already?

Regards,
  Reinhard

=========================================================================
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% CA 94945, U.S.A., +1(415)492-9861, for further information.
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% sRGB color space derived from the public domain HP sample.

currentglobal true setglobal

/sRGB
[ /CIEBasedABC
  3 dict begin
    /WhitePoint [ 0.9505 1 1.0890 ] def % D65

    /DecodeLMN [  % sRGB gamma transform 
      { dup 0.03928 le { 12.92321 div } { 0.055 add 1.055 div 2.4 exp } ifelse }
      bind dup dup ] def

    /MatrixLMN [ % sRGB to XYZ (D65) matrix (ITU-R BT.709-2 Primaries)
      0.412457 0.212673 0.019334
      0.357576 0.715152 0.119192
      0.180437 0.072175 0.950301 ] def
  currentdict end
] 
/ColorSpace defineresource pop

setglobal
=========================================================================


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Reinhard Kotucha                            Phone: +49-511-3373112
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