\documentclass{article}
\usepackage{graphicx}
\newsavebox{\ImageBox}
\begin{document}
	\savebox{\ImageBox}{\includegraphics{rose.eps}}
	\makeatletter
	\newcommand\wdWithoutUnit{\wd\ImageBox\@gobble}
	\newcommand\htWithoutUnit{\ht\ImageBox\@gobble}
	\makeatother
	\begin{picture}(\wdWithoutUnit,\htWithoutUnit)
	  	\setlength{\unitlength}{1cm}
	        \linethickness{1pt}
        	\put(0.5\wdWithoutUnit,0){\line(0,1){\htWithoutUnit}}
        	\put(0,0.5\htWithoutUnit){\line(1,0){\wdWithoutUnit}}
       		\usebox{\ImageBox}
      	\end{picture}%
\end{document}
y