graphics with \setbeamercovered{transparent}

Question

With \setbeamercovered{transparent} covered parts of a slide are displayed transparently. If there is a (small) picture among the text, it is shown as it is. Beamer has only this picture, so it shows this picture. My question: How can I give a gray version of the picture to beamer such that in covered parts of a slide, this gray version is used?

Answer 1

Overlays are the easiest way to replace an image. But you will have to find the right luminosity values yourself, when producing the gray scale version of your image.

\documentclass{beamer}
\usetheme{Warsaw}
\setbeamercovered{transparent}
\setbeamertemplate{navigation symbols}{}
\usepackage{beamerthemeshadow}
\usepackage{tikz}

\begin{document}

    \begin{frame}
        \begin{block}{Theorem}
            Theorem Text Here
        \end{block}

        \vfill \pause 

        \begin{example} 
            \centering
            \includegraphics<-.>[height=0.4\textwidth]{example-image}
            \includegraphics<.(1)->[height=0.4\textwidth]{example-grid-100x100bp}
        \end{example}

        \vfill \pause

        \begin{block}{Corollary}
            Corollary text here
        \end{block}        

    \end{frame}

\end{document}

---

EDIT

And as not asked in the question, this works exactly the same for q.e.d. symbols

\documentclass{beamer}
\usetheme{Warsaw}
\setbeamercovered{transparent}
\setbeamertemplate{navigation symbols}{}
\usepackage{beamerthemeshadow}
\usepackage{tikz}

\setbeamertemplate{qed symbol}{%
    \includegraphics<-.>[width=0.5cm,height=0.5cm]{example-image}
    \includegraphics<.(1)->[width=0.5cm,height=0.5cm]{example-grid-100x100bp}
}

\begin{document}

    \begin{frame}

        \begin{proof}
            \begin{itemize}
                \item First item.
                \item Second item.
                \item Third item.
            \end{itemize}
        \end{proof}     
        \vfill \pause 

        \begin{proof}
            \begin{itemize}
                \item First item.
                \pause
                \item Second item.
                \pause
            \end{itemize}
        \end{proof}

        \vfill \pause

        \begin{block}{Corollary}
            Corollary text here
        \end{block}        

    \end{frame}

\end{document}