Image on full slide in beamer package

This works:

\documentclass{beamer}
\title{test of full size graphic}
\usepackage{tikz}
\usetheme{AnnArbor}

\begin{document}

\begin{frame}
    \maketitle
    Notice the fancy presentation theme.
\end{frame}

{ % all template changes are local to this group.
    \setbeamertemplate{navigation symbols}{}
    \begin{frame}<article:0>[plain]
        \begin{tikzpicture}[remember picture,overlay]
            \node[at=(current page.center)] {
                \includegraphics[keepaspectratio,
                                 width=\paperwidth,
                                 height=\paperheight]{yourimage}
            };
        \end{tikzpicture}
     \end{frame}
}

\begin{frame}
    symbols should be back now
\end{frame}

\end{document}

You have to run beamer twice to get the image centered in the right place. But if you have any other aux-file tricks (e.g., table of contents) you need to do that anyway.

If you're not already using tikz, you can save your image as a pdf and then use \includepdf (part of the pdfpages package). This will get you into trouble if you want to print your slides as an article or handout, though.

If you use article mode with your slides, you'll get the image on a full page of the article PDF too. You probably don't want this. The <article:0> mode specification keeps this frame from being included in any article mode documents. You could also make a separate \includegraphics line for article mode that would format it properly.

The following strategy worked, but not when I had \mode* in operation.

{
\usebackgroundtemplate{\includegraphics[width=\paperwidth]{figure}}
\begin{frame}[plain]
\end{frame}
}

The following seems to work when I have \mode* operating in the document.

\mode<all>
{
\usebackgroundtemplate{\includegraphics[width=\paperwidth]{figure}}
\begin{frame}[plain]
\end{frame}
}
\mode<all>{\usebackgroundtemplate{}}
\mode*

An more light-weight approach (no extra packages, no necessity to compile twice) is to set the page-filling image as background template via \usebackgroundtemplate and then insert an empty [plain] frame.

To restrict the effect of the background changing to a single slide only, we do this inside a TeX group:

\documentclass{beamer}
\usetheme{Madrid}
\begin{document}
    \begin{frame}{Title}
        First frame
    \end{frame}
    {
    \usebackgroundtemplate{\includegraphics[height=\paperheight,width=\paperwidth]{background.jpg}}
    \setbeamertemplate{navigation symbols}{}
    \begin{frame}[plain]
    \end{frame}
    }
    \begin{frame}{Title}
        Third frame
    \end{frame}
\end{document}