# Beamer and monochrome-xcolor

When using the monochrome option for xcolor in a Beamer presentation, the canvas background shows up as entirely black when compiling with pdflatex, but would be entirely white if compiled with xelatex. (I'm using MacTeX 2015):

\documentclass[xcolor={monochrome}]{beamer}
\begin{document}
\begin{frame}
Hello World!
\end{frame}
\end{document}


What's causing the different behavior? Is there any way to get the background white when using monochrome, at least when the canvas background is left as the default?

• Can you try with Adobe Reader if you have it by any chance? – percusse Mar 2 '16 at 10:08
• @percusse I tried opening the pdflatex output with Preview, Skim and Adobe Reader DC (all on Mac OSX El Capitan), the frame is still gloriously black. – LianTze Lim Mar 2 '16 at 14:01

Actually the default background canvas of a beamer presentation is not transparent but filled with the normal text background color, as it is defined as

\setbeamercolor{background canvas}{parent=normal text}


in beamercolorthemedefault.sty. So what you could do is to actually make it transparent by setting

\setbeamercolor{background canvas}{bg=}


Edit:

Or you could use the xcolor option gray instead of monochrome, which seems to be working the same with pdfLaTeX and XeLaTeX.

• Ah thanks -- no idea how I had the impression that it's transparent; I've now edited my question. But this still doesn't quite explain the different behavior between xelatex and pdflatex, right? – LianTze Lim Mar 2 '16 at 14:02
• @LianTzeLim You are right it doesn't explain the different behavior. As far as I understand it, xelatex is in the wrong here, as the monochrome option should set all colors to black hence also white. If you want a grayscale output you should use the option gray. Also test this example with xelatex: \documentclass{article} \usepackage[monochrome]{xcolor} \begin{document} \color{blue}Test \end{document} This does also not work as it should. – Benjamin Mar 2 '16 at 16:39