[XeTeX] cmyk encoded files

[Zdenek Wagner]

2011/11/20 Daniel Greenhoe <dgreenhoe at gmail.com>:
> 2011/11/20 Zdenek Wagner <zdenek.wagner at gmail.com>:
>> No.
>
>> LCMS is a good choice.
> LCMS is "Little Color Management System"?
> (http://www.color.org/opensource.xalter)?
>
Yes.

>> 1. It ensures that the colours you specify in the document will be converted to cmyk.
>> However, the corrections are wrong.
>> 2. xcolor does not look into inserted graphics,...
>
> But what if I hand define all my colors using cmyk syntax like this for example
>     \definecolor{magenta}{cmyk}{0,1,0,0}
> and create all my graphics using pstricks and related packages (with
> no inserted graphics)?
> Then won't the resulting pdf be cmyk compliant and contain exactly the
> colors I defined?
>
That's what I do. Printed colour samples are commercially available.
They are printed on different types of papers and CMYK values are
given. Thus you select the required colour on a proper paper and use
it. Sometimes I select the colour in gimp and then using LCMS convert
the values from RGB to CMYK. Scanned images are also easy. I keep them
as TIF, using LCMS convert them to CMYK and then by tiff2pdf to PDF
that can be included by \includegraphics.

> Dan
>
>
>
>
> 2011/11/20 Zdenek Wagner <zdenek.wagner at gmail.com>:
>> 2011/11/19 Daniel Greenhoe <dgreenhoe at gmail.com>:
>>> Print shops often require pdf files containing color to be encoded
>>> using CMYK colorspace values.
>>>
>>> Version 2.11 of the xcolor package says that cmyk is "supported by
>>> Postscripts directly" (page 8). So if I simply specify
>>>  \usepackage[cmyk]{xcolor}
>>> in the preamble and compile with XeTeX/XeLaTeX, is that sufficient to
>>> ensure the resulting pdf is cmyk encoded?
>>>
>> No.
>>
>> 1. It ensures that the colours you specify in the document will be
>> converted to cmyk. However, the corrections are wrong. If you wish to
>> convert the colours properly, you have to use colour profiles. LCMS is
>> a good choice. Useful ICC profiles come with different products as
>> Adobe Reader, colour printers, scanners etc. They can also be
>> downloaded from the web. Calculations in the xcolor package can only
>> be used if you are satisfied with approximate colours. It is written
>> in the documentation that conversions are device dependent.
>>
>> 2. xcolor does not look into inserted graphics, you have to convert
>> your images to cmyk separately. Again LCMS is a good tool for this
>> purpose.
>>
>>> Secondly, is there any free utility available for checking the
>>> colorspace encoding of pdf files (maybe similar to foolab's pdffonts
>>> for checking embedded fonts).
>>>
>> I have not found any. Since I produce PDF files for printing very
>> often, I calculated that commercial Adobe Acrobat is cheaper than the
>> risk of paying unusable books, thus I have bought it.
>>
>>> Many thanks in advance,
>>> Dan
>>>
>>>
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>>
>>
>>
>> --
>> Zdeněk Wagner
>> http://hroch486.icpf.cas.cz/wagner/
>> http://icebearsoft.euweb.cz
>>
>>
>>
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-- 
Zdeněk Wagner
http://hroch486.icpf.cas.cz/wagner/
http://icebearsoft.euweb.cz