[XeTeX] cmyk encoded files

[Zdenek Wagner]

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