# How to make partially transparent beamercolorbox

In my poster, I added a background picture and make the blocks partially transparent, using the following code

\documentclass[final, 12pt]{beamer}
\usepackage[size=custom,width=120,height=120,scale=1.7,orientation=portrait]{beamerposter}
\usepackage{ragged2e}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{etoolbox}
\apptocmd{\frame}{\justifying}{}{}

\usebackgroundtemplate{\centering \includegraphics[width=\paperwidth, height=\paperheight]{Figure/LG_PKL.jpg}}

\newenvironment<>{varblock}[2][\textwidth]{%
\setlength{\textwidth}{#1}
\begin{actionenv}#3%
\def\insertblocktitle{#2}%
\par%
\usebeamertemplate{block begin}}
{\par%
\usebeamertemplate{block end}%
\end{actionenv}}

\usecolortheme{rose}

\begin{document}
\begin{frame}

\begin{textblock}{}(0.55,0.05)
\begin{center}
\setlength{\textwidth}{113cm}
\begin{beamercolorbox}{block body}
gdsghfdhdfgh
\end{center}
\end{beamercolorbox}
\end{center}
\end{textblock}

\begin{textblock}{}(0.2,1.15)%
\begin{varblock}[35cm]{\textbf{1. Introduction}}
\justifying
Space for discussion.
\end{varblock}
\end{textblock}

\end{document}


It works nice with block,but I need to make the beamercolorbox's also partially transparent.Can any one please help me?

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Your example doesn't work! Please correct this. –  Marco Daniel May 13 '12 at 10:16

Your example code has some errors and won't work. However, I could reprouce your problem with a simple modification to your sample code (I changed some settings to make my example simpler, but this is not relevant to the problem nor to the solution):

\documentclass[final, 12pt]{beamer}
\usepackage[size=custom,width=10,height=10,scale=.7,orientation=portrait]{beamerposter}
\usepackage{graphicx}
\usepackage{textpos}

\usecolortheme{rose}

\usebackgroundtemplate{%
\centering\includegraphics[width=\paperwidth, height=\paperheight]{ctanlion}}

\newenvironment<>{varblock}[2][\textwidth]{%
\setlength{\textwidth}{#1}
\begin{actionenv}#3%
\def\insertblocktitle{#2}%
\par%
\usebeamertemplate{block begin}}
{\par%
\usebeamertemplate{block end}%
\end{actionenv}}

\begin{document}

\begin{frame}
\begin{textblock}{}(0.55,0.05)
\setlength\textwidth{5cm}
\begin{beamercolorbox}[wd=5cm]{block body}
some test text\\
some test text
\end{beamercolorbox}
\end{textblock}

\vfill

\begin{textblock}{}(0.2,1.15)%
\begin{varblock}[5cm]{Introduction}
Space for discussion.
\end{varblock}
\end{textblock}
\end{frame}

\end{document}


The result shows that the beamercolobox color hides the background image:

To preven this problem, you can simply use \pgfsetfillopacity{0.65} inside the frame environment (or inside the textblock environment that holds the offending box if you want to keep the change local):

\documentclass[final, 12pt]{beamer}
\usepackage[size=custom,width=10,height=10,scale=.7,orientation=portrait]{beamerposter}
\usepackage{graphicx}
\usepackage{textpos}

\usecolortheme{rose}

\usebackgroundtemplate{%
\centering\includegraphics[width=\paperwidth, height=\paperheight]{ctanlion}}

\newenvironment<>{varblock}[2][\textwidth]{%
\setlength{\textwidth}{#1}
\begin{actionenv}#3%
\def\insertblocktitle{#2}%
\par%
\usebeamertemplate{block begin}}
{\par%
\usebeamertemplate{block end}%
\end{actionenv}}

\begin{document}

\begin{frame}
\pgfsetfillopacity{0.65}

\begin{textblock}{}(0.55,0.05)
\setlength\textwidth{5cm}
\begin{beamercolorbox}[wd=5cm]{block body}
some test text\\
some test text
\end{beamercolorbox}
\end{textblock}

\vfill

\begin{textblock}{}(0.2,1.15)%
\begin{varblock}[5cm]{Introduction}
Space for discussion.
\end{varblock}
\end{textblock}
\end{frame}

\end{document}


CTAN lion drawing by Duane Bibby.

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Thank you so much......I am really grateful to you...... –  Mahzabin May 14 '12 at 1:27
@Gonzalo Medina: I tried your code but curiously they do not work for me, because both give opaque boxes, both for the beamercolorbox than for the varbox. Can you help me understand this? –  simona Sep 18 '12 at 19:13
@simona Sure! But I will need to see a minimal version of your code. I think it would be best to open a fresh question. Follow-up questions like this are more than welcome! Please use the "Ask Question" link for your new question; there you can link to this question to provide the background. Don't forget to add the relevant code to the new question. –  Gonzalo Medina Sep 18 '12 at 19:43
This is working for me, but the text is also partially transparent... I would prefer for readability to have the background semi-transparent, as it is, but the text with full opacity... Any idea? –  user32804 Jun 26 at 1:45