diff --git a/Makefile b/Makefile
index c2d1c39de2a9e4161e761151ad0d06b0ecc90c63..34f33f7ba2e1681eddeff86cb5a346c87ecd6cd6 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 all: presentation.pdf
 
 presentation.pdf: presentation.tex header.tex
-	latex -shell-escape presentation.tex
+	pdflatex -shell-escape presentation.tex
 
 clean:
 	rm presentation.{aux,bcf,dvi,log,nav,out,run.xml,snm,toc}
diff --git a/header.tex b/header.tex
index 1c4b3fc7d210e8fb784454e8f03e02079e700a75..9b2f10f448407708e464d38eab2bdb4dafc89db7 100644
--- a/header.tex
+++ b/header.tex
@@ -17,6 +17,7 @@
 \usepackage{array} % Pour générer des tableaux
 \setbeamertemplate{footline}[default]
 \usepackage{multirow}
+\usepackage{graphicx}
 %% symbol in math mode
 \newcommand\NN{\mathbb{N}}
 \newcommand\ZZ{\mathbb{Z}}
diff --git a/img/subversion_logo.jpg b/img/subversion_logo.png
similarity index 100%
rename from img/subversion_logo.jpg
rename to img/subversion_logo.png
diff --git a/presentation.tex b/presentation.tex
index d970719b23a61f6cdfa3f5ca2a20ec37fb833daf..63525a34bb93a56eff8d6e21cb6793445339b284 100644
--- a/presentation.tex
+++ b/presentation.tex
@@ -32,13 +32,13 @@ time so that you can recall specific versions later.
   \end{itemize}
   \begin{columns}
     \begin{column}{0.3\textwidth}
-  \includegraphics[width=1.1\textwidth]{./img/subversion_logo.jpg}
+  \includegraphics[width=\textwidth]{./img/subversion_logo.png}
     \end{column}
     \begin{column}{0.3\textwidth}
-  \includegraphics[width=1.1\textwidth]{./img/git_logo.jpg}
+  \includegraphics[width=\textwidth]{./img/git_logo.jpg}
     \end{column}
     \begin{column}{0.3\textwidth}
-  \includegraphics[width=0.6\textwidth]{./img/mercurial_logo.jpg}
+  \includegraphics[width=0.7\textwidth]{./img/mercurial_logo.jpg}
     \end{column}
   \end{columns}
 \end{frame}
@@ -50,7 +50,7 @@ time so that you can recall specific versions later.
 {\bf Local}\\
 \vspace{-2em}
 \begin{center}
-  \includegraphics[width=0.6\textwidth]{./img/vcs_local}\\
+  \includegraphics[width=0.6\textwidth]{./img/vcs_local.png}\\
   \begin{itemize}
     \item can be done manually, but error prone
     \item need to collaborate with other developers
@@ -61,7 +61,7 @@ time so that you can recall specific versions later.
 {\bf Centralized}\\
 \vspace{-2em}
 \begin{center}
-  \includegraphics[width=0.6\textwidth]{./img/vcs_centralized}\\
+  \includegraphics[width=0.6\textwidth]{./img/vcs_centralized.png}\\
   \begin{itemize}
     \item In case of failure of the central serveur or network, we lose access
     to the version database
@@ -72,7 +72,7 @@ time so that you can recall specific versions later.
 {\bf Distributed}\\
 \vspace{-2em}
 \begin{center}
-  \includegraphics[width=0.6\textwidth]{./img/vcs_distributed}\\
+  \includegraphics[width=0.6\textwidth]{./img/vcs_distributed.png}\\
 \end{center}
 }
 \end{frame}