So funktioniert es:
\documentclass{article}
\usepackage{pdflscape}
\usepackage{graphicx}
\begin{document}
\begin{landscape}
\begin{minipage}{\linewidth}
\includegraphics%
[width=\linewidth,height=\textheight,keepaspectratio]%
{example-image-a}
\end{minipage}
\end{landscape}
\begin{landscape}
\begin{minipage}{\linewidth}
\includegraphics%
[width=\linewidth,height=\textheight,keepaspectratio]%
{example-image-b}
\end{minipage}
\end{landscape}
\end{document}
![alt text][1]
Wenn du TikZ brauchst um auf die Bilder drauf zu malen, bietet es sich an [diese Frage von TeX.SX](https://tex.stackexchange.com/questions/9559/drawing-on-an-image-with-tikz) zu adaptieren.
\documentclass{article}
\usepackage{tikz}
\usepackage{pdflscape}
\usepackage{graphicx}
\begin{document}
\begin{landscape}
\begin{minipage}{\linewidth}
\begin{tikzpicture}
\node[anchor=south west,inner sep=0pt] (img) {%
\includegraphics
[width=\linewidth,height=\textheight,keepaspectratio]%
{example-image-a}%
};
\begin{scope}[x={(img.south east)},y={(img.north west)}]
\draw[red,ultra thick,rounded corners] (0.3,0.2) rectangle (0.7,0.8);
\end{scope}
\end{tikzpicture}
\end{minipage}
\end{landscape}
\begin{landscape}
\begin{minipage}{\linewidth}
\begin{tikzpicture}
\node[anchor=south west,inner sep=0pt] (img) {%
\includegraphics
[width=\linewidth,height=\textheight,keepaspectratio]%
{example-image-b}%
};
\begin{scope}[x={(img.south east)},y={(img.north west)}]
\draw[blue,ultra thick,rounded corners] (0.3,0.2) rectangle (0.7,0.8);
\end{scope}
\end{tikzpicture}
\end{minipage}
\end{landscape}
\end{document}
![alt text][2]
[1]: http://texwelt.de/wissen/upfiles/test_253.pnghttp://texwelt.de/wissen/upfiles/test_253.png
[2]: http://texwelt.de/wissen/upfiles/test_254.png
