Colored and opaque image background in Beamer with foilhead

Question

My .tex is this

\documentclass[12pt,xcolor={usenames}]{beamer}
\setbeamercovered{transparent}
\setbeamertemplate{caption}[numbered]
\usepackage[spanish,es-tabla,es-nodecimaldot]{babel}
\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc} 
\normalfont
\usepackage{beamerfoils}
\usepackage{tikz}
\usepackage{graphicx}
\usepackage{courier}
\usefonttheme{serif}

\definecolor{darkturquoise}{rgb}{0.0, 0.81, 0.82}


\beamertemplatetheoremsnumbered
\setbeamerfont{institute}{size=\small}
\title{{\bf\LARGE\color{white}Title Slide}\newline{\bf\color{white}Faculty}\newline{\bf\Large\color{white}Course}}
\author{\bf\color{white}Lecturer
\newline{\scriptsize\href{mailto:name@university.edu}{name@university.edu}}}
%\titlegraphic{\includegraphics[scale=0.3]{UW_logo}}
\date{}

\setbeamercovered{invisible}

\begin{document}

{\setbeamercolor{background canvas}{bg=darkturquoise}
\maketitle}


\foilhead{Second slide}
No color here

\foilhead{Third slide}
{\setbeamercolor{background canvas}{bg=darkturquoise}
Color here}

\foilhead{Fourth Slide}
\begin{center}
{\Large opaque image here, bluish if possible}
\end{center}
\endfoil
\end{document}

I'm trying to give my third slide the same background color as the first one (darkturquoise), but I can't. Also, I'd like to put some image on my fourth slide as background (full slide). Also, is it possible to give it a bluish (darkturquoise) tint at the same time?

Maybe this image:

I have seen some solutions but they cannot be applied to the foilhead enviroment, I guess.

Answer 1

Do you really need to use beamerfoils? Why don't you just use standard frames? Things are much better documented then:

\documentclass[12pt,xcolor={usenames}]{beamer}
\setbeamercovered{transparent}
\setbeamertemplate{caption}[numbered]
\usepackage{tikz}

\definecolor{darkturquoise}{rgb}{0.0, 0.81, 0.82}

\beamertemplatetheoremsnumbered
\setbeamerfont{institute}{size=\small}

\title{\texorpdfstring{
        \textbf{\LARGE\color{white}Title Slide}\newline
        \textbf{\color{white}Faculty}\newline
        \textbf{\Large\color{white}Course}
    }{Title Slide -- Faculty -- Course}
}
\author{\texorpdfstring{
        \textbf{\color{white}Lecturer\newline
        \scriptsize\href{mailto:name@university.edu}{name@university.edu}}
    }{Lecturer: name@university.edu}
}
\date{}

\setbeamercovered{invisible}

\begin{document}

{\setbeamercolor{background canvas}{bg=darkturquoise}
\maketitle}

\begin{frame}{Second slide}
No color here
\end{frame}

{\setbeamercolor{background canvas}{bg=darkturquoise}
\begin{frame}{Third slide}
Color here
\end{frame}}

{\usebackgroundtemplate{
\begin{tikzpicture}[remember picture, overlay]
    \node[at=(current page.center)] {
        \includegraphics[keepaspectratio,
                         width=\paperwidth,
                         height=\paperheight]{example-image-a}
    };
    \fill[darkturquoise!25, blend mode=multiply] (current page.north east) rectangle (current page.south west);
\end{tikzpicture}
}
\begin{frame}{Fourth slide}
{\Large opaque image here, bluish if possible}
\end{frame}}

\end{document}

Some notes:

• Do not use \bf, this macro is deprecated. Use \textbf instead.
• It is probably a good idea to give an alternative PDF string for the title and author, so that it is printed in a reasonable way in the PDF's meta data.
• In general, you need to state the background color setting before starting the frame. So, you should create some scope using {}.
• Finally, you can place the image and overlay it with some tint using TikZ in combination with \usebackgroundtemplate as shown in the example above.

---

If you still want to stick with beamerfoils: Since setting the background color involves scoping, you need to end the relevant frame explicitly using \endfoil or using the \frame macro. Therefore, this should work:

{\setbeamercolor{background canvas}{bg=darkturquoise}
\foilhead{Third slide}
Color here
\endfoil
}

and also:

{\setbeamercolor{background canvas}{bg=darkturquoise}\frame{
\foilhead{Third slide}
Color here
}}

Similarly, you can do:

{\usebackgroundtemplate{
\begin{tikzpicture}[remember picture, overlay]
    \node[at=(current page.center)] {
        \includegraphics[keepaspectratio,
                         width=\paperwidth,
                         height=\paperheight]{example-image-a}
    };
    \fill[darkturquoise!25, blend mode=multiply] (current page.north east) rectangle (current page.south west);
\end{tikzpicture}
}
\foilhead{Third slide}
{\Large opaque image here, bluish if possible}
\endfoil
}