can fontspec work with CMYK colors?

Question

Can fontspec be used to manage a document's fonts if the fonts need to use the CMYK color model? The fontspec documentation, section 6.1, says that fontspec uses RGB colors. My experimentation (MWE below) seems to confirm that fontspec will convert CMYK colors passed to it into noticeably different RGB equivalents.

PDF output of MWE (using XeLaTeX, fontspec, xcolor):

MWE:

\documentclass[a4paper]{article} 

\usepackage{fontspec}
\usepackage{xcolor}

\definecolor{mycyan}{cmyk}{1,0,0,0}
\definecolor{mymagenta}{cmyk}{0,1,0,0}
\definecolor{myyellow}{cmyk}{0,0,1,0}
\definecolor{myblack}{cmyk}{0,0,0,1}

\begin{document} 

Without fontspec:

\textcolor{mycyan}{\rule{10pt}{10pt}}
\textcolor{mycyan}{XXX Cyan text (CMYK 1,0,0,0)}

\textcolor{mymagenta}{\rule{10pt}{10pt}}
\textcolor{mymagenta}{XXX Magenta text (CMYK 0,1,0,0)}

\textcolor{myyellow}{\rule{10pt}{10pt}}
\textcolor{myyellow}{XXX Yellow text (CMYK 0,0,1,0)}

\textcolor{myblack}{\rule{10pt}{10pt}}
\textcolor{myblack}{XXX Black text (CMYK 0,0,0,1)}

With fontspec:

\textcolor{mycyan}{\rule{10pt}{10pt}}
\fontspec[Color=mycyan]{Arial} XXX Cyan text (CMYK 1,0,0,0)

\textcolor{mymagenta}{\rule{10pt}{10pt}}
\fontspec[Color=mymagenta]{Arial} XXX Magenta text (CMYK 0,1,0,0)

\textcolor{myyellow}{\rule{10pt}{10pt}}
\fontspec[Color=myyellow]{Arial} XXX Yellow text (CMYK 0,0,1,0)

\textcolor{myblack}{\rule{10pt}{10pt}}
\fontspec[Color=myblack]{Arial} XXX Black text (CMYK 0,0,0,1)

\end{document}

Answer 1

Fontspec can work with CMYK colors, if you use \textcolor instead of fontspec's Color option:

\documentclass{article}

\usepackage{xcolor}
\usepackage{fontspec}

\definecolor{mycyan}{cmyk}{1,0,0,0}

\begin{document}

Without fontspec:

\textcolor{mycyan}{\rule{10pt}{10pt}}
\textcolor{mycyan}{XXX Cyan text (CMYK 1,0,0,0)}

With fontspec:

\textcolor{mycyan}{\rule{10pt}{10pt}}
\textcolor{mycyan}{\fontspec{Arial} XXX Cyan text (CMYK 1,0,0,0)}

\end{document}