http://sourcingfactory.com/?bankispaniy=je-cherche-un-homme-riche-pour-m%27aider&8a5=68 Auto size of images in Beamer class.

femmes celibataires sur chatou \usepackage{letltxmacro} \makeatletter \def\maxwidth{\ifdim\Gin@nat@width>\linewidth\linewidth\else\Gin@nat@width\fi} \makeatother \AtBeginDocument{ \LetLtxMacro\Oldincludegraphics\includegraphics \renewcommand{\includegraphics}[2][]{% \Oldincludegraphics[#1,width=\maxwidth]{#2}} }

http://tex.stackexchange.com/questions/67434/redefine-includegraphics-for-beamer#comment143600_67434