# Beamer - How to set frametitle box translucent so that backeground image can be seen blurred

everybody. I'm a newbie of beamer. I have encountered a problem as the title depicted. I've tried to search similar questions, but none of those can be applied to frametitle box. For example, \addtobeamertemplate{frametitle}{\pgfsetfillopacity{0.5}}{\pgfsetfillopacity{1}}, this command works, but the color of letters fades too (see following pic). So, could anybody help me solve this problem? thx a lot.

\documentclass{beamer}
\usetheme{CambridgeUS}
\usecolortheme{dolphin}

\begin{document}
\title{My title}
\author{author}

\usebackgroundtemplate{\includegraphics[width=\paperwidth]{background.jpg}}

\begin{frame}[plain]  %empty title page
\titlepage
\end{frame}

\begin{frame}
\frametitle{Outline}
\tableofcontents
\end{frame}
\end{document}

• I'm sorry that I've chosen a not so distinguishing background image – Oearth Sep 29 '15 at 6:22
• Welcome to TeX.SX. Would you mind to provide us with a minimum code where we can make experiments? – Ignasi Sep 29 '15 at 6:47
• Demo code is added. thx. – Oearth Sep 29 '15 at 7:23

The solution I've found (credits to Gradient to transparent (horizontal) for beamer frametitle) consists in changing frametitle definition and fixing there two different opacities, one for title beamercolorbox and another for \insertitle inside it.

Once you know which frametitle template want to use, adapt it.

\documentclass{beamer}
\usetheme{CambridgeUS}
\usecolortheme{dolphin}

\makeatletter
\setbeamertemplate{frametitle}
{
\ifbeamercolorempty[bg]{frametitle}{}{\nointerlineskip}%
\@tempdima=\textwidth%
\pgfsetfillopacity{.7}       %<------ fix filling opacity
\begin{beamercolorbox}[sep=0.3cm,left,wd=\the\@tempdima]{frametitle}
\usebeamerfont{frametitle}%
\vbox{}\vskip-1ex%
\if@tempswa\else\csname beamer@fteleft\endcsname\fi%
\strut\pgfsetfillopacity{1}\insertframetitle\strut\par%  <---- text opacity
{%
\ifx\insertframesubtitle\@empty%
\else%
{\usebeamerfont{framesubtitle}\usebeamercolor[fg]{framesubtitle}\insertframesubtitle\strut\par}%
\fi
}%
\vskip-1ex%
\if@tempswa\else\vskip-.3cm\fi% set inside beamercolorbox... evil here...
\end{beamercolorbox}%
}
\makeatother

\begin{document}
\title{My title}
\author{author}

\usebackgroundtemplate{\includegraphics[width=\paperwidth]{lion.jpg}}

\begin{frame}[plain]  %empty title page
\titlepage
\end{frame}

\begin{frame}
\frametitle{Outline}
\tableofcontents
\end{frame}
\end{document}


• Thank you for your reply. It works perfectly. I appreciate it very much. I have found that link, too. But unfortunately I still don't know how it works. So, I have to post my question here. Next time I will try to fix by myself :) – Oearth Sep 30 '15 at 0:45