\documentclass[a4paper,12pt,titlepage]{scrartcl}
\usepackage[utf8x]{inputenc}
\usepackage[ngerman]{babel}
\usepackage{amsmath}
\usepackage{t1enc}
\usepackage{graphicx}
\usepackage{wrapfig}
\usepackage{subfig}
\usepackage{clrscode}
\usepackage{calc}
\usepackage{lastpage}
\usepackage{hyperref}
\usepackage{underscore}
\usepackage{floatflt}
\usepackage{fancyhdr}
\usepackage{setspace}
\usepackage{changepage}
\usepackage{listings}
\usepackage{framed}
%\usepackage{underscore}

\begin{document}

\begin{figure}[hb]
  \includegraphics{foo_bar.png}
\end{figure}

\end{document}