Beamer - Transparent footline?

Question

I am using a picture as a background for beamer slides. I would like to have my name and page numbers at the bottom of the slide. I do not like the bottom bar to cover the background image. Is it possible to make the bottom bar in transparent colour with names and page numbers visible?

These are themes I am using in the example:

\usetheme{Boadilla}
\usefonttheme{structurebold}
\usecolortheme{seagull}

Answer 1

Here is a solution based on the redefinition of the footline, and the use of \pgfsetfillopacity{<value>} (0=transparent, 1=opaque).

MWE

\documentclass{beamer}
\usetheme{Boadilla}
\usefonttheme{structurebold}
\usecolortheme{seagull}

\setbeamertemplate{footline}
{
  \leavevmode%
  \hbox{%
    \pgfsetfillopacity{0}\begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{author in head/foot}%
      \usebeamerfont{author in head/foot}\pgfsetfillopacity{1}\insertshortauthor~~(\insertshortinstitute)
    \end{beamercolorbox}%
    \pgfsetfillopacity{0}\begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,center]{title in head/foot}%
      \usebeamerfont{title in head/foot}\pgfsetfillopacity{1}\insertshorttitle
    \end{beamercolorbox}%
    \pgfsetfillopacity{0}\begin{beamercolorbox}[wd=.333333\paperwidth,ht=2.25ex,dp=1ex,right]{date in head/foot}%
      \usebeamerfont{date in head/foot}\pgfsetfillopacity{1}\insertshortdate{}\hspace*{2em}
      \insertframenumber{} / \inserttotalframenumber\hspace*{2ex}
    \end{beamercolorbox}}%
  \vskip0pt%
}

\title{Title}
\author{Author}
\institute{Institute}
\date{\today}

\begin{document}

\begin{frame}
\maketitle
\end{frame}

\end{document}

Output Obviously you will have to add your background picture but the grey bars are gone and they should be transparent!