\documentclass[a4paper,ngerman]{scrartcl}
\usepackage{babel}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{graphicx}
\usepackage{xcolor}

\begin{document}
Test.
\includegraphics[clip, trim=1cm 1cm 1cm 1cm, 
width=\textwidth]{testimg.pdf}
\end{document}