\documentclass{article}
\usepackage{pdfpages}
\usepackage{tikz}
\usetikzlibrary{calc}
\begin{document}
\newcommand*\zeilen{5}
\newcommand*\spalten{4}
\newcommand\Gitternetzlinien{%
\thispagestyle{empty}%
\begin{tikzpicture}[remember picture,overlay,shift=(current page.south west)]
\draw[gray,ultra thick] \draw[gray] let
\p{ll} = (current page.south west),
\p{ur} = (current page.north east),
\n{xlen} = {veclen(\x{ll},\x{ur})},
\n{ylen} = {veclen(\y{ll},\y{ur})}
in
(\p{ll}) grid[xstep=\n{xlen}/\spalten,ystep=\n{ylen}/\zeilen] (\p{ur});
\end{tikzpicture}%
}
\includepdf[
fitpaper=true,
pagecommand=\Gitternetzlinien,
width={\spalten pt*50},
mm},
height={\zeilen pt*50},
mm},
]{5.png}
\end{document}
[<img src="http://texwelt.de/wissen/upfiles/test_390.png" style="max-width:100%;"/>][1]
[![alt text][1]][1]
[1]: http://texwelt.de/wissen/upfiles/test_390.pnghttp://texwelt.de/wissen/upfiles/test_392.png
