\pdfoutput =0
\let \origdocument \document 
\let \EndPreamble \endinput 
\def \document {\endgroup \endinput }
\input {example}
\usepackage [active,tightpage]{preview}
\let \document \origdocument 
\pagestyle {empty}
\begin {document}
\centering \null \vfill 
\begin {preview}
\or 
\includegraphics []{\relax }
\end {preview}
\vfill \end {document}

