How do I make this document follow the CMYK standard?

Question

I've tried some scripts and various tricks I found online, but I'm starting to be near my wit's end.

If I do identify -verbose mwe.pdf | grep Colorspace, I get Colorspace: sRGB. I need the CMYK for a print shop.

What to do?

\documentclass{article}
\usepackage{xcolor}
\definecolor{textcolour}{cmyk}{0.6042,0.6875,0.0000,0.8118} % dark
\definecolor{bgyellow}{cmyk}{0, 0, 0.10, 0} % light yellow 

\begin{document}
\pagecolor{bgyellow}
\textcolor{textcolour}{Foo}
\end{document}

Answer 1

CMYK is not a standard. Print shops will not (only) require CMYK, but a real standard document like PDF/X-4. The most important requirement for that standard is colour management. See this example to get an idea what needs to be done.

In easier words: By choosing a colour profile you define how values like 0.6042,0.6875,0.0000,0.8118 are converted to physical colour. This ensures that

1. your document is printed the same way in all (good) print shops.
2. The colours match against an absolute standard. I.e. the university logo looks the same as on other coloured things (documents, walls, labels) created by different tools and printing processes.

Using PDF/X-3 or -4 you can embed RGB images. The print shop will convert the colour values for their machine using the profile you supplied in the PDF.