Color in PDFs created from LaTeX that shouldn't be there

Question

I am a publisher who works with PDFs that authors submit that were created from LaTex. Often the PDF is in color and the author can't fix this issue. Has anyone had this issue and is there a quick fix I can point our authors too?

Answer 1

You could remove \usepackage{xcolor} or \usepackage{color} from the preamble, and see what breaks. But the chances are that loading colour-support is actually done by the graphicx package (manual). This package supports an option monochrome which should do what you want. To apply this option just change \usepackage{graphicx} to

\usepackage[monochrome]{color}
\usepackage{graphicx}

The colour model used is unlikely to be the issue as a simple

\documentclass{article}
\begin{document}
Hello world
\end{document}

is in the sRGB colour space according to identify (ImageMagick):

test.pdf PDF 595x842 595x842+0+0 16-bit sRGB 1.503MB 0.000u 0:00.002

in fact even with \usepackage[cmyk]{xcolor} we still get sRGB according to ImageMagick. This is all on Tex Live 2015/Windows.

As the expert (David Carlisle) pointed out in a comment below, none of this will deal with colour in images. Some images may look monochrome but actually have colour components (scans for example). In an answer to a related question I linked to a script that finds colour pages in a pdf by comparing the RGB channels of each pixel. This may help you track down the offending pages, and hopefully the offending figures (if they are the issue).

For simply forcing pdfs to monochrome or greyscale, they are some suggestions at superuser, but they would need to be used with care.