It would be easier to let LaTeX generate a flowchart instead of generating / importing a png file. Thus, you will not have problems with resolution or under-sampling, and everything will be in vector format.
You can use the TikZ package of the LaTeX package. The following example is provided on texexample.net .
\documentclass{article} \usepackage[latin1]{inputenc} \usepackage{tikz} \usetikzlibrary{shapes,arrows} \begin{document} \pagestyle{empty} % Define block styles \tikzstyle{decision} = [diamond, draw, fill=blue!20, text width=4.5em, text badly centered, node distance=3cm, inner sep=0pt] \tikzstyle{block} = [rectangle, draw, fill=blue!20, text width=5em, text centered, rounded corners, minimum height=4em] \tikzstyle{line} = [draw, -latex'] \tikzstyle{cloud} = [draw, ellipse,fill=red!20, node distance=3cm, minimum height=2em] \begin{tikzpicture}[node distance = 2cm, auto] % Place nodes \node [block] (init) {initialize model}; \node [cloud, left of=init] (expert) {expert}; \node [cloud, right of=init] (system) {system}; \node [block, below of=init] (identify) {identify candidate models}; \node [block, below of=identify] (evaluate) {evaluate candidate models}; \node [block, left of=evaluate, node distance=3cm] (update) {update model}; \node [decision, below of=evaluate] (decide) {is best candidate better?}; \node [block, below of=decide, node distance=3cm] (stop) {stop}; % Draw edges \path [line] (init) -- (identify); \path [line] (identify) -- (evaluate); \path [line] (evaluate) -- (decide); \path [line] (decide) -| node [near start] {yes} (update); \path [line] (update) |- (identify); \path [line] (decide) -- node {no}(stop); \path [line,dashed] (expert) -- (init); \path [line,dashed] (system) -- (init); \path [line,dashed] (system) |- (evaluate); \end{tikzpicture} \end{document}