# [Xy-pic] Default color model

Tue Aug 3 18:26:35 CEST 2010

Hi Vadim and Ross,

if you are willing to use the PDF driver instead of Postscript, there is
an easy solution: Use the xcolor package with a color space as a package
option. This will convert all colors to this color space. For example:

\documentclass{article}
\usepackage[gray]{xcolor}
\usepackage[matrix, color, pdf]{xy}
\begin{document}
\xymatrix{*[green]\hbox{green} & *[yellow]\hbox{yellow}}
\end{document}

Regards,

Daniel

> Hi Ross,
>
> thank you for the explanation.
>
>> Why do you need this?
>>
>> Once before I had to do this, since a publisher objected to having RGB in the PDF.
>> Is yours a similar problem?
>
> Yes, it's exactly my case.
>
>> It was necessary to edit the PostScript dictionary file that is imported by dvips, changing a single specification of '0 0 0 setrgb' to '1 setgray'.
>> Xy-pic has a command \dumpPSdict which gives a local copy of the PostScript dictionary, which you can then edit for the next run (with the \dump... command now commented). Consult the Xy-pic Reference Manual, for information about the PostScript drivers and back-end support.
>
> I used your recipe with \dump and \usePSheaders.  There's no explicit
> "0 0 0 setrgb" in the dump, so is it the line
>
> /xycolor{0 1 2{xycolarray exch get}for setrgbcolor}def
>
> that I have to change?  And is
>
> /xycolor{0 setgray}def
>
> a suitable replacement (it looks fine in my case, but probably I'm
> breaking something)?
>
> Thank you again,
>